Howdy, first you need to make sure your role has the "Advanced Notifications" permission under Roles & Permissions in the Dashboard.
Then when you go to Edit Profile -> Notification Preferences, you'll see the ability to get notified of all discussions and/or comments on a per-category basis at the bottom of the list.
Comments
Then when you go to Edit Profile -> Notification Preferences, you'll see the ability to get notified of all discussions and/or comments on a per-category basis at the bottom of the list.