When you set up two factor authentication, a code is generated that is entered into apps such as Google Authenticator to give you that second factor of authentication, ‘something you have’.
Given that many of us update phones every couple of years, migrating your Google Authenticator credentials is an important issue to consider when you set up your account. Here are some options that will avoid the pain & frustration:
1. Copy the authentication codes to a very safe & secure place. If you have a copy of the codes, they can be re-entered to provide access to the new device.
2. Use the ‘Move authenticator to a different phone’ feature. Access the 2-step verification page, click the Move to a different phone link, and scan the QR code or enter your credentials into a new phone. Your old authentication app will stop working. Other services that use Google Authenticator may not offer this feature, so you may need to disable and re-enable your account.
3. Disable & Re-enable Two-Step Authentication. To do so, click the Remove link on the 2-step verification page. This temporarily disables two-factor authentication. Once the app is set up on the new device, re-enable two-factor authentication & enter the codes on the new devices. Luckily, Google no longer resets your application-specific passwords – even if you disable and re-enable Google Authenticator, your application-specific passwords will remain valid.