Photoshop Tool Bar Problem

I know this is going to sound really stupid, but this is driving me crazy. Whenever I click on an item on the Photoshop toolbar (you know, the thing on the left), it'll show the expanded menu --- Like if I click on the Pencil Tool, it'll automatically expand the menu and show the Brush Tool, and it's annoying, I don't want the menu to expand the things I click on, I only want them to expand if I hold down. Any idea on how to fix this annoyance without having to re-install?

Hope someone can help. :\