It's not actually a bug, we have something on the forums that helps us protect ourselves from spambots. You need to have at least 30 messages on the forums before you can edit a thread you made or your signature. Once you have 30 messages on the forums, you should be able to do whatever you tried doing.
I know this can be an inconvenience but once you hit 30 messages on the forums you should be completely fine from then on. If you do find yourself having problems after you have hit 30 messages, this could be because something wrong is on our side so we may need to contact an administrator. If this is happening to you, let any of the staff know and they will be able to help you from then on.
Thread locked.