Why did my username change?

Go to profile setting and change username

Did you edit your forum Profile?

1. Go back to your Profile page and change your screen name back to what it was before you edited your Profile. 

2. Hit the SAVE button to commit changes

https://community.adobe.com/t5/user/myprofilepage/tab/personal-profile:personal-info

Hope that helps.

See this thread:

https://community.adobe.com/t5/back-room-discussions/my-forum-name-got-changed-and-i-can-t-change-it-back/m-p/14808993

is 2 fa enabled?

can you change it back?