I changed my signature few hours ago, adding some text below the mini banner but the changes won't show up. I still see only the mini banner, even though in the sCode preview it looks changed. I used the same code on my profile and there it works.

Edit: it works now, this can be locked ^^

Just for future reference, forum signatures are on a bit of a cache, so it can take a bit of time before you see the changes appear on actual forum posts. But as long as it's displaying correctly on the preview page, it should show the changes on the forums eventually (once the cache updates).