Sycamore,
From what I understand of these things, yes, if you use the "back" button all the "new" markings should stay as you are going back to that page as it was before. However, when you click on the "go to top" or "go to topic" links, the "new" should only disappear from the one(s) you just read. My problem is that it disappears from a lot more than just the ones I've read.
Glad to hear others are having the problem as well.