The Forum Signature system has been implemented and will show up on any NEW post you make. Before, the headline in your QuadCRAZY profile would act as the Forum Signature (displayed at the bottom of every post you make). That has now been changed.
To edit your signature, when you are logged into the forums, look at the top navigation bar and click on "UserCP". Then "Edit Signature"
*Note: Your new Signature will only appear in NEW posts that you make from the time you make the signature.