优化

app/src/main/java/io/legado/app/help/config/AppConfig.kt

@@ -365,7 +365,7 @@ object AppConfig : SharedPreferences.OnSharedPreferenceChangeListener {
 
     val ignoreAudioFocus get() = appCtx.getPrefBoolean(PreferKey.ignoreAudioFocus, false)
 
-    val onlyLatestBackup get() = appCtx.getPrefBoolean(PreferKey.onlyLatestBackup, false)
+    val onlyLatestBackup get() = appCtx.getPrefBoolean(PreferKey.onlyLatestBackup, true)
 
     val doublePageHorizontal: String?
         get() = appCtx.getPrefString(PreferKey.doublePageHorizontal)