Further, if you click on the little icon (double down arrow, I think) to the left of the title, it will take you to newest unread post in that thread.
You can look under the Forum Tab which is just below the Tree House name at the top of the screen to get to the different catagories of posts.
I read frequently, so I know which of the new threads I'm most interested in, and if I am not interested, it drops to the old but unread area. You can also Mark All Forums read, if you want to clear it out, and just keep up on the current postings. FWIW.