If you'd like to have your username changed, just post a thread
in this forum instead of PMing a super mod or admin. I figure it's better that way, since then other people will see the topic and won't be so clueless as to who this person with a new name is
There's 2 ways that you can have your name changed. You can have your Displayed Name
changed, or you actual username. Your displayed name is just what you're seen as to the rest of the forum; you still login with your "real" username, and nobody else can take it or use it. This is more for temporary name changes, such as theme weeks.
The other way is having your actual
username changed. With this, you're giving up your old one. Also when it's changed, the forum will reset your password and email it to you. So make sure your email address is valid
If it does go wrong or something, you miss the email or don't get it or some other reason, you can always go to RMRK's IRC Channel
and message a super mod or admin for help there.