If you need to reinstall the Mobile Authenticator, but haven’t removed a previous version from your account, you’ll need to use the Restore feature. If you have iCloud Keychain enabled, you can restore your authenticator through Cloud Sync.
Locate and write down your Serial Number and Restore Code before using this feature. Open the menu and select Serial & Restore if you're on an Android device. If you're on an Apple device, select Restore Code.
After you reinstall the Mobile Authenticator, you can set up or restore the application. Select Restore and enter your Serial Number and Restore Code.
Note: If you're attempting to restore the application from a new device, you may be asked to log in from a trusted device instead.