Here is a quick way you can stay connected with forum categories. If you go to the top right of each Category you will see a drop down with a circle in it. Once you click this, you will get several options, each with a different fidelity of notification. Choose the level you prefer and you will be notified when there are new posts available.
once you do this, you will see notifications show up in top right of your avatar as a blue icon with number of notifications.