I'm assuming you're flying a DGIV since it changes the controls in a certain mode...
What you need to do is go to the 2D panel with all the buttons (you cycle through the views using F8). In the top left of the panel you'll see a switch with a bunch of modes... Off, Pitch, Elevon & Gear, RCS lin, RCS rot, Atm Auto.
RCS are those "little rockets", acronym for Reaction Control System.
What you wanna do is set it to Elevon & Gear on this button. That will enable the control surfaces. Then you wanna switch to the other view and in the top left corner of the screen click on ROT. That will turn on the RCS rotation mode. You will not have control of the ship at high and low velocities, in atmosphere and space.