Can you help us to define your problem.
when you talk about the “group forums” and the “general forums” do you mean ones set up using buddypress, or how have these been set up?
talkemily.com
If you take a look at this website there is a “Forum” section and “Group” section.
From the home page, where you can post on the activity stream, there is the option to post on the “Groups” but not the “Forums”.
Forums: Discussions, Buy & Sell, Housing, Jobs, Events, Clubs
Group: Emily Carr University Alumni, Film, Design, Animation, etc etc
ex) user would be able to post to the “Emily Carr University Alumni” group but not the “Buy & Sell” forum.
Presuming it is buddypress you are using, then your question would be better on their support site.
I don’t have buddypress experience.