Sony vaio laptop sound button

Hello,

I need help! For some reason there is no sound button on my laptop. Its the weirdest thing! I have to raise the volume throught the computer but I don't think that should be necessary... On the F2 F3 and F4 keys, it shows a little picture of a mute button, a volume up button, and a volume down one, but when I click them my browser bar becomes highlighted and my history shows up on the computer... Could anyone please help?

Thanks!
-Bree.