I couldn't keep up with all the email notifications so I changed my selection to no for this option, "Use e-mail notification by default." Recently, I changed my mind again and changed my selection back to yes and also clicked the submit modifications button. I didn't get any results so I followed Debby's advice to go back again and click no, then click yes, and then click submit modifications. I am still not receiving any email notifications on the threads I am subscribed to. I have been receiving all my other email.