I added one and it didn't show up. I thought perhaps that it would start showing up with new posts after I created it. Again i have posted a few times and it still does not show up.

 

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 is how the old vB 2.x that we used was tweaked, as it 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.