The notifications that stay under "older events" is supposed to stay just like that. As I stated in another thread we MAY put a hide/remove option there in the future.  

When you have new events (the little color burst notifications is there showing you have new events since you last checked) and you click to go to that notifications page then you will ONLY see the events that occured since the last time you had any new events, all the rest are not shown, they are under that "Older Event" button so you don't have to see them unless you choose to click on that older event button. If you go back to that page without any NEW events then it will show the last 10 events that occurred for you and if you want to see more than the last 10 then click the older events button and it will show you even older ones than the 10 .

 

Stacey