The Online Discussion Forum has a range of options for when you will receive notifications to forum topics. Notifications can be requested at the "Category" level, or at an individual "Topic" level.

Category Watching

To be notified whenever a comment is made for any topic in a category click the bell shaped icon at the top left of the page when you are browsing the list of all topics for a category and choose Watching.

Topic Watching

If you want to follow one or just a few topics in a category, select the topic you are interested in and click on the bell shaped icon at the bottom of the topic  and choose Watching

Select Muted to stop receiving notifications on a topic or category.