On the Board Index it shows what forums have new posts by the orange icon. If I entered a forum on the previous version of NT and I saw the topics marked as new posts and i then left the forum without actually entering the topics, the index would then update to show there are no new posts.
In the current version it forces me to enter every single topic to remove the new topic orange notifier. I am not sure if this is a setting in my control panel (I could not find it). I preferred the previous method as it allowed me to quickly go through each forum to check if topics I was interested have been updated.
It's a minor difference, and I'm not totally sure of the longterm affects. Such as what If I never enter a topic in each board? Would all boards eventually remain orange? I'm not sure if after a certain period of time this goes away, but currently each day more and more forums are getting marked as new to the point of all the forums marked with a new post notifier.