The camera is mounted on a variable friction arm. There is only one knob used to adjust the camera.
By loosening the knob you can freely move the camera up and down, as well as, backwards and forward.
Use the knob on the arm to re-position the camera.
Support the camera with your left hand while loosening the knob. Once the knob is slightly loosened you can reposition the camera to the desired location. Re-tighten the knob to lock the arm and secure the camera at that position.