Here's something that happens all the time: 

1. I go to the forum and I see that a thread was answer. 
2. I go to the thread and read the answer.
3. I reply to that answer. 
4. Now I see I have a notification on my notification bell (that was already there before but I hadn't seen it). 
5. I click the notification bell and the notification is about the answer I just read (#2) and replied to (#3). 

My feature suggestion would be to make the item inactive in the notification list and menu after I've accessed that item - even if I didn't go to my notification menu. 

There was a clear notifications application but its out of date. I'm sure I found a new one but can't find it again