I just checked this out as best I can (click on "Control Center" in the "Go to" bar near the top of the board), and it appears to me that in order to change your username, you need to reregister under the new name.
I vaguely remember that this is what I did several years ago, when I changed my username.
(You can change your email address, and also your password, by going to your present profile; both of these are very easy to change once you get to your profile page, after you click on "Control Center".)
Edited 1 time(s). Last edit at 04/24/2018 08:55PM by Tevai.
You can't change your user name, but the way I got around it was to change to the screen name I wanted instead, and that's what shows up when you post. Just go to Control Center and it's easy to change to a different screen name.
Edited 1 time(s). Last edit at 04/24/2018 10:02PM by contrarymary.