I don't know how to turn off 3g on iphone 4s ios 7?

Since iv updated my iphone from ios 6 to ios 7, my battery life has decreased a lot and i think it might be because of 3g but i can't find it. Can someone please tell me where 3g is and tell me how to stop my battery life decreasing so fast?

Settings>cellular> turn off cellular data

In IOS6 you go to setting>general>cellular and toggle the 3G slider.

If this is not available in IOS 7 then it might be in the new menu that you get by sliding your finger up from the bottom of the screen, whist on the home screen.

Ok, go on Settings>Mobile>Enable 3G and turn It to either on or off. Glad to help!

I also have the iPhone 4S.
When you try to turn off the 3G switch in settings
It turns it's self back on.
Is there a different method of defeating 3G?