Why do my app icons keep rearranging on iPhone?

When you perform a factory reset on an iPhone — like when you choose "Erase All Content and Settings" — the device is wiped clean.

This means:

• Home Screen layout: It returns to the default layout that comes with iOS — just like a brand-new iPhone.
• Apps and app data: All third-party apps and their data are erased. Built-in Apple apps remain, but any settings and data tied to them are reset.
• Media and files: Photos, videos, music, and documents stored locally on the device are also deleted.
• Settings: Network settings, privacy preferences, and any system configurations return to their original defaults.

After the reset, you have two options:

1. Set up as a new iPhone: No previous data is restored. You start fresh.
2. Restore from a backup:

• • iCloud backup: App data, settings, messages, and media are downloaded from iCloud. The apps themselves are re-downloaded from the App Store, not directly from the backup.
  • Computer backup (Finder/iTunes): This restores the backup’s app data and settings. The apps still get re-downloaded from the App Store.

So while the data comes from the backup, the apps themselves always download fresh from the App Store, ensuring you get the latest versions.