It may be that your account is illegal, which makes it impossible to change the nickname normally. Parents are advised to contact Tik Tok customer service to help you lift the restrictions. Or modify the signature and clear it. There should be no sensitive words in the signature. Maybe there is something wrong with the ID, so I can't get through. Try not to change the ID first, one by one! Delete all nicknames when you change them, and then save the rest. Nicknames still exist.

Of course, you can also download and install again, and then log in to see the specific situation. If there is no violation and the information is normal, or there is no way, you can contact the official customer service and ask them to help solve it.