There's really nothing you can do, unless there's some hidden "Mark Forums Unread" feature that I've never noticed before.
But it's not really a big deal... if the forums suddenly become a bit congested, I'll click "Mark Forums Read", to make it easier to find recently updated threads.
But it's not really a big deal... if the forums suddenly become a bit congested, I'll click "Mark Forums Read", to make it easier to find recently updated threads.