ok your having your signiture where it will not show up that is because you didnt look in your profile and edit it to where it is attached to all your posts so here is a Tutorial for you to FIX THIS:
1. Go To Your Profile
2. Click the Preferences Tab
3. Scroll do to where it says Always attach my signature :(it will be the 11th thing for you to change)
4. Click Yes
5. Save