1. Check Tencent official website. Tencent may be in the system maintenance stage. Usually at this stage, users can't change their personal signatures, avatars and nicknames.
2, check whether qq is the latest version, if not updated.
3. See if there is anything wrong with your internet speed.
4. See if your personalized signature needs harmonious words and characters.
5. It may be that the network environment is not good, or there may be something wrong with Tencent's server. It'll be all right in a minute.
6. The number of words and characters of personalized signature is too long, which exceeds the limit.
7. If the above reasons are excluded, it must be that there are sensitive words in your personality signature, that is, forbidden words. Please check for yourself.