When Super-heat is above its normal range or too HIGH this means that the refrigerant levels are low or TXV is too closed meaning the path the refrigerant flows through is being restricted too much at the TXV.   If the Super-heat is below normal range or too LOW it means pressures or refrigerant levels are to high or the path the refrigerant flows through is wide open and the TXV is not restricting this path enough.