Make sure your scooter is fully charged; you'll want to charge it 4-5 hours.
Check that the speed setting has been changed by pressing the Riding Mode and checking the speed setting on the display. The first gear goes to 9.3mph, second goes to 12.4mph, and the third goes to 15.5mph.
Test your scooter on a flat surface to determine it's true speed.
If you find that your scooter is still slow, please send a request to Customer Service. You may need a replacement scooter.