I added a signature this morning just to find that it only shows up new posts, not old one (Before the sig was added). (That pretty much sums it up)
It's been a while, but I'm pretty sure the first time I put a new sig up it only showed up in my new posts. But then... It's been a while.
Think of it as a foot print. If you change shoes it changes your footprint. But it doesn't change where you have already walked.
I've always been used to the signature changing the same way an avatar would (Or title). (Though this is the first time I put a sig up on this site) Thanks for clearing that up, question answered.