Problem with the function buttons

I recently formatted my macbook pro, and am now trying to reset all the settings to what they were before. One of my problems is that the function buttons don't react as "F1 to F8" buttons. As an example, if I push on F9, the light around all the buttons turns down. But in system preferences, it says that is supposed to separate the different open applications. Before I formatted, I needed to push on "fn" at the same time to reduce the light, volume etc. Can anyone tell me how to change that?

Try going to sys pref/keyboard , mouse
select the keyboard tap and then check the box labeled "use all F1 F2 etc.:

Hope this helps
Clay

Thanks it did the trick.