How do I filter "Recent Posts" list?

How do I filter "Recent Posts" list?

At the top of any forum page, hover your pointer over the link in the brown bar that says "Forum:"

In any forum page at the top right of the thread list you will see a small drop down menu. To see recent posts you can click either "New Posts" or "Activity Feed."

There is an Activity Feed on the main forum homepage as well (the one with the carousel). It is updated with Real Time.