I just updated to the new version of firefox and some of the tabs,ie; drop down back tab..are gone and the search space is a mile long. I like the older version how do I go back?

I downloaded the new version of fire fox because the update screen said to. Now the down arrow beside the back arrow is gone so you have to close the page when you want to go back/ leave a secure page. also the search space is almost all the way across the screen. I also don't want and can't get rid of the yahoo search space on top.