There is also a useful tool on the forums in the Forum Theme I use, Babylon and that is 'Show new replies to your posts.' So any replies to topics that you either start or contribute to would be listed when you click the link.
I don't know if it is as readily accessible in the other forum themes, available through the Profile button, Look and Layout Preferences, Current Theme: So another hidden gem 
I now think that the lack of email notifications is related to this statement in one of the email notices:
"More replies may be posted, but you won't receive any more notifications until you read the topic."Sometimes, I actually remember to "log out" of the Avast! forums instead of staying logged in "forever." If I view the responses without logging back in, the notifications cease. My mistake.
I did look for the forum themes, but could not find them.
Perhaps because I am using the Home version? That made no sense ... how could my version of Avast! have anything to do with the way the forums operate? I think I need caffeine!
