Is the "signature" the same as my user ID? Can I change my user ID?

You don't need to change your user ID.
- go to "user cp" (top of the page on the left)
- click "Edit Signature"
- type in how you would like your signature to appear (no last names or e-mails allowed for safety reasons)
- click "save changes" when finished

You can also follow the same procedure for editing your avatar or profile.

Hope this helped.

If you wish to change your user id, please pm me or Andrew :)