how can i change it?

U can't. There was a topic, but I can't find it atm. Ask mod to change it.

ask the helpers or an admin/moder

awww, strange :S, a time after i saw in my profile a button, change nickname. Thanks for replys guys

That was before they moved to vBulletin.

I saw this and i was like wow.. What kind of person can change his own name in the client... Then i read it through. To get a forum name change i would just PM an moderator and ask them to.