Since Guest accounts are stored locally on your device, you risk losing your game progress and in-game purchases if you lose or upgrade your device. Linking your account preserves your previously saved game data, allowing you to use your data on another device after logging in to the linked account.
Follow these steps to link an account:
1. Tap the gear icon at the top of the main screen to open the Settings menu.
2. Tap the yellow + icon at the top of the screen.
3. Choose an account type to link. You will be taken to the account provider to log in and confirm the account linking.
4. After confirming, you will be directed back to Call of Duty: Mobile to log in to your linked account.
Once your account is linked, be sure to choose your linked account instead of Guest whenever you play Call of Duty: Mobile.