On the side of the MouseBlocker PRO unit is a small “mode” button. This button is what you use to change to the different sound levels.
From the OFF position, press the mode button once to get to the first level (85dB) then again to get to the second level (10 times louder, 95 dB) then again for the third level (115dB or more than 100 times louder than level 1). Press again for the OFF position.