Account Help

[Fadmad]

http://www.opticraft.net/index.php/topic,9418.0.html
This is the forum link. Salas said i could change my forum name. So I changed this one and logged onto my old account, tried to change the name but it said user already taken. So I went back to this one and saw that the username CANNOT be changed only the display on. Can anyone help me out here? Thanks