So in order to change you're name you can get on your email and contact Brainly (you can get the contact email by searching for Brainly contact info on the internet) and send them a message stating "I want to change my username". Once you do this US Support will email you back and ask you to give three examples of a new username you could want and they will also include instructions on how they want you to do it.
Hope this helps.
-Northstar
