I liked that you could watch a post and then get notified when someone commented. That way if there was a question that someone asked, and you wanted to know the answer too, you could be notified that someone might have an answer.
Go to "Forum Actions" in the blue bar at the top of this page (right under the board's name banner), click the down arrow, then on General Settings" for the settings page. Scroll down to "Messaging & Notification"/"Default Thread Subscription Mode". Click the down arrow on the box to choose your notification mode. You have five choices. Once your made your changes, and you may want to look around on that page for other changes you may want to make, scroll all the way to the bottom and press the "Save" button to save your changes.
Maybe you want to watch a topic, without posting to it. Go to the top of the topic page, and choose "Thread Tools", click on the down arrow, and "Subscribe to this thread".
Hope this helps!