By the way, if the "new" icons on all the archive threads are annoying you, you can nuke the lot by going to the forum's front page and clicking on "MARK ALL MESSAGES AS READ" towards the lower right of the page. Make sure you've read any new messages on threads that interest you first, though, because hitting that button removes every "new" icon across the entire forum. After that, the "new" icons will slowly come back - but only on active threads - as people continue to post and the moderators continue to archive material from Aimoo OuchToo.
EDIT: It turns out that there are several options for marking things as read or unread, depending on where you are in the forum. Here's a list of what I've found so far:
1. On the front page of the forum, there's a "MARK ALL MESSAGES AS READ" link towards the lower right of the page. It marks everything in the entire forum as read, so use it with caution.
2. In the different topic areas, such as "Talk" or "Cafe", there are "MARK READ" links near the "NEW TOPIC" ones. These mark everything in that area as read, but leave the rest of the forum alone.
3. In any given thread, you'll find "MARK UNREAD" links near the "REPLY" links. These mark the current thread as unread, which restores the "new" icon for that thread. Note that this also sends you back to the thread list, so don't be surprised when that happens.
Option 3 can be handy if you find an interesting new post in a thread, but you haven't got time to read it right now, so you want a reminder to come back to it later.