IE9 Favorites Question - Rather Frustrating

I have all my Favorites showing on the left side of my screen on IE9. I have number folders and inside each have the websites that correspond with that folder. I had them set so that when I opened one folder and selected a website that folder would close automatcially when I opened another folder. In other words all the folders could be seen but their contents could not.

I do not remember changing anything but today, the folders are not behaving in this manner and stay open .... HELP!

Thanks!