I took a look at the older post that you linked in this thread and it seems like you did not check off the option to add your signature to your posts. Other user's old posts probably updated because they had this box check off, even for the older posts. I went to that last post (in linked thread) and added your signature for you.
Thanks, but it seems like people would have to do this for every single old post, right? That's odd, because from what I remember, everyone's old posts would contain their new sigs. I can't imagine they sat there and checked the box individually on old posts.
After you did that, it's still just showing up for that specific post. Not any of my other older posts.
It's not a big deal, but this does seem to be a new change to the board.