it will only post my Sig in my first post and not after that. is there any reason for that?

 

By default, if you have Show Signature set to Yes in your userCP, when you create a new thread, the "Show you Signature" will automatically be checked, which is an option below where you type your message. Your signature will then show.

However, if you reply to an existing thread, and if you want your signature to display, you will have to manually place check in the box for "Show your Signature" each time, which is the option below the where you type your message.

This helps reduce redundant use of one's signatures, especially for those who may post in the same thread multiple times. It's been this way for several years.