Your Tik Tok number was changed to someone else's account after changing your mobile phone, because the Tik Tok account that he logged in before his mobile phone did not exit, and then you click Exit, enter your mobile phone number, and the login can be changed.

Tik Tok is its Tik Tok ID, which consists of a series of numbers. A mobile phone number can only register one Tik Tok number. If you want to register other Tik Tok numbers, you can only do so after unbinding.