2
Notification Method: When you monitor e.g. a forum, how would you like to receive notifications of updates?
Default Notification Mode: All/once/once until login
These two fields have nothing to do with WHAT the user is notified of, only HOW these notifications are sent.
You'll need to figure out a way to enable this specific notification ("notify me of any new posts" - the full text is admin only, but can be changed of course) for all users.