"Attach signature" checkbox displaying and signatures not displaying

I'm pretty sure they're related so smooshing them into the same issue :)

The way I'm trying to set things up is so the signature gets posted in every post.

- got "forum topic" checked for the show signatures for nodes and comments for box
- selected "always" for show user's signature in the per conversation box
- am not allowing users to choose their own global defaults
- am using Advanced Forum so got the "automatically add..." option switched off.

All signatures in posts prior to upgrading the live site to D6 are showing up fine. New forum topics however have the checkbox down the bottom asking if the user wants to use their signature and the link that says this setting can be changed in their account, which it can't because I said no :) If box is checked, signature is attached to forum post, if it's not, it doesn't. New comments aren't displaying the signatures either, possibly because I haven't allowed the checkbox to be shown for comments, because I want them to just be used all the time without letting users have the option to use it or not. I'm horrible like that ;)

Is there some setting I've managed to miss or is this an actual problem? It's working as it should be on my local dev but I haven't been able yet to work out what the difference is.

thanks! :)