To change the linked device, you must first remove the current device link and then link the new device to your account.
To do this, follow the steps in How can I deactivate two-factor authentication and unlink my device? andHow do I set up two-factor authentication for my account?
To do this, follow the steps in How can I deactivate two-factor authentication and unlink my device? andHow do I set up two-factor authentication for my account?