I would like to know, on the main Stack Exchange overview I would like to know is it possible to change my username? I don't like the current one right now and I would like to know if I could find a way to change it?
If you're talking about this site, Meta Stack Exchange, then all you need to do is go to your profile, click "edit", and set your display name to whatever you want.
If you're talking about any other meta site in the network, you have to edit your display name on the actual Q&A site that meta's attached to (that is, for RolePlaying Games meta, you should edit your profile on Roleplaying Games).
You can also apply your changes to all Stack Exchange sites if you'd rather not have different display names on different sites.