Porsche Boxster Owner's Manual page 109

Push operating lever slightly up or down until
the desired speed is reached.
upwards: speed is increased
downwards: speed is decreased
Note
Holding the lever up or down for a longer period will
adjust the speed in steps of 6 mph (10 km/h).
Push operating lever forward.
Switching the acoustic warning signal off
Select "LIMIT active" with the operating lever.
Push operating lever forward.
Display:
107
Controls, Instruments