diff --git a/app-expo/src/app/(main)/chapter/[id].tsx b/app-expo/src/app/(main)/chapter/[id].tsx
index 43608dd..c364fa6 100644
--- a/app-expo/src/app/(main)/chapter/[id].tsx
+++ b/app-expo/src/app/(main)/chapter/[id].tsx
@@ -23,7 +23,13 @@ import {
   ScreenHeader,
 } from '@/components/screen-header';
 import { ScreenGutter } from '@/constants/layout';
+import { useMemoirReadingSettings } from '@/core/memoir-reading-settings-context';
 import { useTypography } from '@/core/typography-context';
+import type {
+  MemoirReadingBackground,
+  MemoirReadingFontFamily,
+  MemoirReadingFontSize,
+} from '@/core/settings/memoir-reading-settings';
 import { useAppSettings } from '@/hooks/use-app-settings';
 import {
   MarkdownRenderer,
@@ -137,11 +143,7 @@ function StorySegmentCover({
   );
 }
 
-type FontSize = 'small' | 'default' | 'large';
-type FontFamily = 'serif' | 'sans';
-type BackgroundTheme = 'white' | 'sepia';
-
-const FONT_FAMILIES: Record<FontFamily, string> = {
+const FONT_FAMILIES: Record<MemoirReadingFontFamily, string> = {
   serif:
     Platform.select({ ios: 'Georgia', android: 'serif', default: 'serif' }) ??
     'serif',
@@ -153,7 +155,7 @@ const FONT_FAMILIES: Record<FontFamily, string> = {
     }) ?? 'sans-serif',
 };
 
-const BACKGROUND_COLORS: Record<BackgroundTheme, string> = {
+const BACKGROUND_COLORS: Record<MemoirReadingBackground, string> = {
   white: READING_COLORS.background,
   sepia: READING_COLORS.backgroundSepia,
 };
@@ -192,12 +194,12 @@ function ReadingSettingsModal({
 }: {
   visible: boolean;
   onClose: () => void;
-  fontSize: FontSize;
-  fontFamily: FontFamily;
-  backgroundColor: BackgroundTheme;
-  onFontSizeChange: (v: FontSize) => void;
-  onFontFamilyChange: (v: FontFamily) => void;
-  onBackgroundChange: (v: BackgroundTheme) => void;
+  fontSize: MemoirReadingFontSize;
+  fontFamily: MemoirReadingFontFamily;
+  backgroundColor: MemoirReadingBackground;
+  onFontSizeChange: (v: MemoirReadingFontSize) => void;
+  onFontFamilyChange: (v: MemoirReadingFontFamily) => void;
+  onBackgroundChange: (v: MemoirReadingBackground) => void;
   t: (key: string) => string;
 }) {
   const insets = useSafeAreaInsets();
@@ -359,6 +361,16 @@ export default function ChapterScreen() {
   const { id } = useLocalSearchParams<{ id: string }>();
   const insets = useSafeAreaInsets();
   const { largeText } = useAppSettings();
+  const {
+    preferences: {
+      fontSize,
+      fontFamily,
+      background: backgroundTheme,
+    },
+    setFontSize,
+    setFontFamily,
+    setBackground: setBackgroundTheme,
+  } = useMemoirReadingSettings();
   const typography = useTypography();
   const { width } = useWindowDimensions();
   const { t } = useTranslation('memoir');
@@ -367,12 +379,8 @@ export default function ChapterScreen() {
   const deleteChapter = useDeleteChapter();
 
   const [settingsVisible, setSettingsVisible] = useState(false);
-  const [fontSize, setFontSize] = useState<FontSize>('default');
-  const [fontFamily, setFontFamily] = useState<FontFamily>('serif');
-  const [backgroundColor, setBackgroundColor] =
-    useState<BackgroundTheme>('white');
 
-  const bgColor = BACKGROUND_COLORS[backgroundColor];
+  const bgColor = BACKGROUND_COLORS[backgroundTheme];
 
   if (isLoading) {
     return (
@@ -610,10 +618,16 @@ export default function ChapterScreen() {
         onClose={() => setSettingsVisible(false)}
         fontSize={fontSize}
         fontFamily={fontFamily}
-        backgroundColor={backgroundColor}
-        onFontSizeChange={setFontSize}
-        onFontFamilyChange={setFontFamily}
-        onBackgroundChange={setBackgroundColor}
+        backgroundColor={backgroundTheme}
+        onFontSizeChange={(v) => {
+          void setFontSize(v);
+        }}
+        onFontFamilyChange={(v) => {
+          void setFontFamily(v);
+        }}
+        onBackgroundChange={(v) => {
+          void setBackgroundTheme(v);
+        }}
         t={t as (key: string) => string}
       />
     </View>
diff --git a/app-expo/src/core/memoir-reading-settings-context.tsx b/app-expo/src/core/memoir-reading-settings-context.tsx
new file mode 100644
index 0000000..2a35065
--- /dev/null
+++ b/app-expo/src/core/memoir-reading-settings-context.tsx
@@ -0,0 +1,99 @@
+import React, {
+  createContext,
+  useCallback,
+  useContext,
+  useEffect,
+  useMemo,
+  useState,
+  type PropsWithChildren,
+} from 'react';
+
+import {
+  DEFAULT_MEMOIR_READING_PREFERENCES,
+  type MemoirReadingBackground,
+  type MemoirReadingFontFamily,
+  type MemoirReadingFontSize,
+  type MemoirReadingPreferences,
+} from '@/core/settings/memoir-reading-settings';
+import {
+  getMemoirReadingPreferences,
+  setMemoirReadingPreferences,
+} from '@/core/settings/app-settings';
+
+type MemoirReadingSettingsContextValue = {
+  ready: boolean;
+  preferences: MemoirReadingPreferences;
+  setFontSize: (v: MemoirReadingFontSize) => Promise<void>;
+  setFontFamily: (v: MemoirReadingFontFamily) => Promise<void>;
+  setBackground: (v: MemoirReadingBackground) => Promise<void>;
+};
+
+const MemoirReadingSettingsContext =
+  createContext<MemoirReadingSettingsContextValue | null>(null);
+
+export function MemoirReadingSettingsProvider({ children }: PropsWithChildren) {
+  const [preferences, setPreferences] = useState<MemoirReadingPreferences>(
+    DEFAULT_MEMOIR_READING_PREFERENCES,
+  );
+  const [ready, setReady] = useState(false);
+
+  useEffect(() => {
+    let cancelled = false;
+    void (async () => {
+      const loaded = await getMemoirReadingPreferences();
+      if (cancelled) return;
+      setPreferences(loaded);
+      setReady(true);
+    })();
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+
+  const persistAndSet = useCallback(async (patch: Partial<MemoirReadingPreferences>) => {
+    await setMemoirReadingPreferences(patch);
+    setPreferences((prev) => ({ ...prev, ...patch }));
+  }, []);
+
+  const setFontSize = useCallback(
+    (v: MemoirReadingFontSize) => persistAndSet({ fontSize: v }),
+    [persistAndSet],
+  );
+
+  const setFontFamily = useCallback(
+    (v: MemoirReadingFontFamily) => persistAndSet({ fontFamily: v }),
+    [persistAndSet],
+  );
+
+  const setBackground = useCallback(
+    (v: MemoirReadingBackground) => persistAndSet({ background: v }),
+    [persistAndSet],
+  );
+
+  const value = useMemo(
+    () => ({
+      ready,
+      preferences,
+      setFontSize,
+      setFontFamily,
+      setBackground,
+    }),
+    [ready, preferences, setFontSize, setFontFamily, setBackground],
+  );
+
+  return (
+    <MemoirReadingSettingsContext.Provider value={value}>
+      {children}
+    </MemoirReadingSettingsContext.Provider>
+  );
+}
+
+export function useMemoirReadingSettings(): MemoirReadingSettingsContextValue {
+  const ctx = useContext(MemoirReadingSettingsContext);
+  if (!ctx) {
+    throw new Error(
+      'useMemoirReadingSettings must be used within MemoirReadingSettingsProvider',
+    );
+  }
+  return ctx;
+}
diff --git a/app-expo/src/core/providers.tsx b/app-expo/src/core/providers.tsx
index e4d7780..8357e04 100644
--- a/app-expo/src/core/providers.tsx
+++ b/app-expo/src/core/providers.tsx
@@ -2,6 +2,7 @@ import React, { type PropsWithChildren } from 'react';
 
 import { initApiClient } from '@/core/api/client';
 import { AppSettingsProvider } from '@/core/app-settings-context';
+import { MemoirReadingSettingsProvider } from '@/core/memoir-reading-settings-context';
 import { NetworkError } from '@/core/api/types';
 import { tokenManager } from '@/core/auth/token-manager';
 import { config } from '@/core/config';
@@ -62,7 +63,9 @@ initApiClient({
 export function AppProviders({ children }: PropsWithChildren) {
   return (
     <AppQueryProvider>
-      <AppSettingsProvider>{children}</AppSettingsProvider>
+      <AppSettingsProvider>
+        <MemoirReadingSettingsProvider>{children}</MemoirReadingSettingsProvider>
+      </AppSettingsProvider>
     </AppQueryProvider>
   );
 }
diff --git a/app-expo/src/core/settings/app-settings.ts b/app-expo/src/core/settings/app-settings.ts
index 12854bd..d0204e1 100644
--- a/app-expo/src/core/settings/app-settings.ts
+++ b/app-expo/src/core/settings/app-settings.ts
@@ -10,11 +10,18 @@ import { supportedLanguages, type AppLanguage } from '@/i18n/resources';
 
 import { THEME_NAMES, type ThemeName } from '@/constants/theme-bridge';
 
+import {
+  mergeMemoirReadingPreferences,
+  parseMemoirReadingPreferences,
+  type MemoirReadingPreferences,
+} from './memoir-reading-settings';
+
 const KEY_LANGUAGE = 'app_settings_language';
 const KEY_LARGE_TEXT = 'app_settings_large_text';
 const KEY_DARK_MODE = 'app_settings_dark_mode';
 const KEY_THEME_NAME = 'app_settings_theme_name';
 const KEY_TTS_SPEAK_DEFAULT = 'app_settings_tts_speak_default';
+const KEY_MEMOIR_READING = 'app_settings_memoir_reading';
 
 const webFallback: Record<string, string> = {};
 
@@ -95,5 +102,20 @@ export async function setTtsSpeakDefault(value: boolean): Promise<void> {
   await setStored(KEY_TTS_SPEAK_DEFAULT, value ? 'true' : 'false');
 }
 
+export async function getMemoirReadingPreferences(): Promise<MemoirReadingPreferences> {
+  const raw = await getStored(KEY_MEMOIR_READING);
+  return parseMemoirReadingPreferences(raw);
+}
+
+export async function setMemoirReadingPreferences(
+  patch: Partial<MemoirReadingPreferences>,
+): Promise<void> {
+  const raw = await getStored(KEY_MEMOIR_READING);
+  const current = parseMemoirReadingPreferences(raw);
+  const next = mergeMemoirReadingPreferences(current, patch);
+  await setStored(KEY_MEMOIR_READING, JSON.stringify(next));
+}
+
 export { supportedLanguages, THEME_NAMES };
 export type { AppLanguage, ThemeName };
+export type { MemoirReadingPreferences } from './memoir-reading-settings';
diff --git a/app-expo/src/core/settings/memoir-reading-settings.ts b/app-expo/src/core/settings/memoir-reading-settings.ts
new file mode 100644
index 0000000..0245d7c
--- /dev/null
+++ b/app-expo/src/core/settings/memoir-reading-settings.ts
@@ -0,0 +1,70 @@
+export type MemoirReadingFontSize = 'small' | 'default' | 'large';
+
+export type MemoirReadingFontFamily = 'serif' | 'sans';
+
+export type MemoirReadingBackground = 'white' | 'sepia';
+
+export interface MemoirReadingPreferences {
+  fontSize: MemoirReadingFontSize;
+  fontFamily: MemoirReadingFontFamily;
+  background: MemoirReadingBackground;
+}
+
+export const DEFAULT_MEMOIR_READING_PREFERENCES: MemoirReadingPreferences = {
+  fontSize: 'default',
+  fontFamily: 'serif',
+  background: 'white',
+};
+
+const FONT_SIZES: MemoirReadingFontSize[] = ['small', 'default', 'large'];
+const FONT_FAMS: MemoirReadingFontFamily[] = ['serif', 'sans'];
+const BACKGROUNDS: MemoirReadingBackground[] = ['white', 'sepia'];
+
+function isFontSize(v: unknown): v is MemoirReadingFontSize {
+  return typeof v === 'string' && FONT_SIZES.includes(v as MemoirReadingFontSize);
+}
+
+function isFontFamily(v: unknown): v is MemoirReadingFontFamily {
+  return typeof v === 'string' && FONT_FAMS.includes(v as MemoirReadingFontFamily);
+}
+
+function isBackground(v: unknown): v is MemoirReadingBackground {
+  return typeof v === 'string' && BACKGROUNDS.includes(v as MemoirReadingBackground);
+}
+
+export function parseMemoirReadingPreferences(
+  raw: string | null,
+): MemoirReadingPreferences {
+  if (raw == null || raw.trim() === '') {
+    return { ...DEFAULT_MEMOIR_READING_PREFERENCES };
+  }
+  try {
+    const parsed: unknown = JSON.parse(raw);
+    if (parsed == null || typeof parsed !== 'object' || Array.isArray(parsed)) {
+      return { ...DEFAULT_MEMOIR_READING_PREFERENCES };
+    }
+    const o = parsed as Record<string, unknown>;
+    const d = DEFAULT_MEMOIR_READING_PREFERENCES;
+    return {
+      fontSize: isFontSize(o.fontSize) ? o.fontSize : d.fontSize,
+      fontFamily: isFontFamily(o.fontFamily) ? o.fontFamily : d.fontFamily,
+      background: isBackground(o.background) ? o.background : d.background,
+    };
+  } catch {
+    return { ...DEFAULT_MEMOIR_READING_PREFERENCES };
+  }
+}
+
+export function mergeMemoirReadingPreferences(
+  base: MemoirReadingPreferences,
+  patch: Partial<MemoirReadingPreferences>,
+): MemoirReadingPreferences {
+  return {
+    fontSize:
+      patch.fontSize !== undefined ? patch.fontSize : base.fontSize,
+    fontFamily:
+      patch.fontFamily !== undefined ? patch.fontFamily : base.fontFamily,
+    background:
+      patch.background !== undefined ? patch.background : base.background,
+  };
+}
diff --git a/app-expo/src/features/memoir/markdown-renderer.tsx b/app-expo/src/features/memoir/markdown-renderer.tsx
index 0bc2913..0a65357 100644
--- a/app-expo/src/features/memoir/markdown-renderer.tsx
+++ b/app-expo/src/features/memoir/markdown-renderer.tsx
@@ -9,6 +9,10 @@ import React from 'react';
 import { Platform, StyleSheet, Text, View } from 'react-native';
 import Markdown from 'react-native-markdown-display';
 
+import type {
+  MemoirReadingFontFamily,
+  MemoirReadingFontSize,
+} from '@/core/settings/memoir-reading-settings';
 import type { ImageAsset } from './types';
 
 const PLACEHOLDER_RE = /\{\{\{\{IMAGE:(.*?)\}\}\}\}|\{\{IMAGE:(.*?)\}\}/g;
@@ -197,8 +201,8 @@ export interface MarkdownRendererProps {
   markdown: string;
   renderedAssets: ImageAsset[];
   coverImageUrl: string | null;
-  fontSize: 'small' | 'default' | 'large';
-  fontFamily: 'serif' | 'sans';
+  fontSize: MemoirReadingFontSize;
+  fontFamily: MemoirReadingFontFamily;
   backgroundColor: string;
   contentWidth: number;
   /** 多故事分段时仅首段下沉首字 */
diff --git a/app-expo/tests/core/settings/memoir-reading-settings.test.ts b/app-expo/tests/core/settings/memoir-reading-settings.test.ts
new file mode 100644
index 0000000..2b629f2
--- /dev/null
+++ b/app-expo/tests/core/settings/memoir-reading-settings.test.ts
@@ -0,0 +1,86 @@
+import {
+  DEFAULT_MEMOIR_READING_PREFERENCES,
+  mergeMemoirReadingPreferences,
+  parseMemoirReadingPreferences,
+} from '@/core/settings/memoir-reading-settings';
+
+describe('parseMemoirReadingPreferences', () => {
+  it('returns defaults for null and empty', () => {
+    expect(parseMemoirReadingPreferences(null)).toEqual(
+      DEFAULT_MEMOIR_READING_PREFERENCES,
+    );
+    expect(parseMemoirReadingPreferences('')).toEqual(
+      DEFAULT_MEMOIR_READING_PREFERENCES,
+    );
+    expect(parseMemoirReadingPreferences('   ')).toEqual(
+      DEFAULT_MEMOIR_READING_PREFERENCES,
+    );
+  });
+
+  it('returns defaults for invalid JSON', () => {
+    expect(parseMemoirReadingPreferences('not json')).toEqual(
+      DEFAULT_MEMOIR_READING_PREFERENCES,
+    );
+  });
+
+  it('returns defaults for non-object JSON', () => {
+    expect(parseMemoirReadingPreferences('[]')).toEqual(
+      DEFAULT_MEMOIR_READING_PREFERENCES,
+    );
+    expect(parseMemoirReadingPreferences('"x"')).toEqual(
+      DEFAULT_MEMOIR_READING_PREFERENCES,
+    );
+  });
+
+  it('fills missing or invalid fields from defaults', () => {
+    expect(parseMemoirReadingPreferences('{}')).toEqual(
+      DEFAULT_MEMOIR_READING_PREFERENCES,
+    );
+    expect(
+      parseMemoirReadingPreferences(
+        JSON.stringify({
+          fontSize: 'huge',
+          fontFamily: 'comic',
+          background: 'black',
+        }),
+      ),
+    ).toEqual(DEFAULT_MEMOIR_READING_PREFERENCES);
+  });
+
+  it('accepts valid partial object', () => {
+    expect(
+      parseMemoirReadingPreferences(
+        JSON.stringify({ fontSize: 'large' }),
+      ),
+    ).toEqual(
+      mergeMemoirReadingPreferences(DEFAULT_MEMOIR_READING_PREFERENCES, {
+        fontSize: 'large',
+      }),
+    );
+    expect(
+      parseMemoirReadingPreferences(
+        JSON.stringify({ background: 'sepia', fontFamily: 'sans' }),
+      ),
+    ).toEqual({
+      ...DEFAULT_MEMOIR_READING_PREFERENCES,
+      background: 'sepia',
+      fontFamily: 'sans',
+    });
+  });
+});
+
+describe('mergeMemoirReadingPreferences', () => {
+  it('applies only defined patch keys', () => {
+    const base = {
+      fontSize: 'small' as const,
+      fontFamily: 'sans' as const,
+      background: 'sepia' as const,
+    };
+    expect(mergeMemoirReadingPreferences(base, { fontSize: 'large' })).toEqual({
+      fontSize: 'large',
+      fontFamily: 'sans',
+      background: 'sepia',
+    });
+    expect(mergeMemoirReadingPreferences(base, {})).toEqual(base);
+  });
+});