For B9 airbrakes, they must be balanced in some way. For instance, if you put 1 large airbrake on each wing's top, the nose will tend to point upwards. My science on airbrakes is not perfect at all, but you can try placing evenly, behind the CoM. If an airbrake is applying drag over/under the CoM, the plane will pitch accordingly. And far gives you the possibility of setting control surfaces as spoilers and flaps by right-clicking them in the SPH.