Hobbit, if you're referring to the "Forum Latest" panel next to the puzzle, it's as Gaye Christine says: the view is updated whenever you switch to a different puzzle. Or, you can update the information whenever you want by clicking on the button
at the top right of the Forum Latest panel.
When you're actually on a Forum page, your latest posts should be visible. To be sure of seeing the latest posts from other people, you may need to click the browser's Reload/Refresh button (or you can press the F5 key on the keyboard in many browsers). However, the little "New" icon seems to go missing occasionally, even when there are new posts.
I hope this answers your problem - if not, please let me know.