Methods/steps to modify the signature:
1 ? As shown below, saving failed.
2 ? It's the level of qq. Two stars, that is, level 2, cannot change the personality signature.
3 ? More than 3 stars can be exchanged.
Qq personalized signature is only visible to yourself:
1) Open mobile QQ, select "I" in the lower right corner, then select "Settings" on the "I" page, and then enter "Permissions and Privacy". (as shown in the figure below)
2) Find "Personalized Signature Synchronous Call" on the "Permission and Privacy" page, and turn on the option to finish. (as shown in the figure below)