On the main forum page, there is a "Mark Forums Read" option that will mark everything read (there are also similar links for sub forums, etc). That way only new topics are highlighted when you return. Many of us use this to mark all the country sub-forums read after we've read the relevant ones.

Got it, thanks!

Additionally, the circle besides the topic shows Blue if I've read all the posts in it, or Red if there are posts since the last time I've looked at that topic. When opening a topic, if there are unread posts then there's a First unread post link just above the first post.