I would suggest that when you click on the title "Questions", the selection on "Active/featured/hot/week/month" should also be reset, same with other Main Menu entires. Simple, clicking on any Main menu item, should completely reset all sub-menus to their default item.
To reproduce: Click on "featured" sub-category under "Questions".
Click on "Questions"
-notice how "featured" is still selected.
My suggestion is that it should not "remember" this, because I Think that most users, like me, prefer clicking "Questions" to come back to the "start page", and same way the other way around, I Think people want to come back to the "start" when they click on a title section (for example, if they click on Unanswered, they want to come back to the "default page" of Unanswered, and not what they were last).