To change the layout of the Academic Forum, first, go to the week you want to open and click the discussion you want to view. Then, at the top of the discussion thread, select to view either the oldest first, the newest first, chats in thread form, or chats in nested form. 

The oldest replies are the earliest replies in order from when the discussion forum was created. The newest replies are the most recent responses in the discussion forum. The threaded view allows you to see who has replied to the discussion thread, and when. And the nested view is the default view of the discussion forums, where you can view all discussions and each response to them.