SMS has a lot of tweakable things that you can do (far more than any other forum software that Ive seen)...
Where I was going wrong is I was looking at the global settings which were fine, and thats why I couldnt see anything earlier.
Once I realised that the reason you couldnt edit, was
only in this forum because it was an "annoucement forum" and therefore it had separate rules which applied
only to this section.. then I was able to tweak the rules locally for this section only too.