Each of the Apollo scooters comes with an LED controlled featuring three gears. Each gear limits the top speed - Gear 1 has the lowest top speed, while Gear 3 is the maximum. Simply press the "Mode" button on your controller to switch gears.
If this does not work, check your advanced settings, namely P2 units, P4 voltage, P6 wheel diameter, P8 power level, and P12 acceleration. For a guide to advanced settings, click here.
For any additional questions, submit a request.