On the top right corner of the forum, click the dropdown button and select Account Settings. Then on the right, click on Notification Settings. From there you can choose whatever notifications you would like to get.
Oh, I'd seen that, I just meant I thought you could turn notifications for different content types (posts, threads, statuses, etc.) on and off for each individual person you follow, I could've sworn I saw it recently but maybe it's just my imagination ^^;