at least on iOS, the fingerprint works in conjunction with a password. You must enter your password and then, for a limited period of time, you can use your fin

at least on iOS, the fingerprint works in conjunction with a password. You must enter your password and then, for a limited period of time, you can use your fingerprint for access. The fingerprint is used to generate something more like a session key. If you change your password, the fingerprint no longer gives you access, you have to reauthenticate with the password before the fingerprint will work again.