JarHQ by default sends notifications only to those who are assigned to a request or in a group assigned to a request. This is so we don't overwhelm everyone's inboxes with messages.
If you would like to be notified of customer replies on requests you're not assigned to, you can easily add yourself as a "follower".
In the request you'd like to be notified on, simply add yourself and/or others who want notifications as a follower to the request.
Make sure to hit "update" when you're done!