On the right hand side of the back screen there is a round multi selector, this controls the placement of your focal point in the viewfinder. Just move it to where you want it. There is also a switch/lever on the outside of the selector with a "L" position or a "-" if you move it to the "L" it with lock the focal point so you can not accidentally move it. It's usually moved by accidentally hitting it with your cheek while looking through the viewfinder when not locked.