It's not difficult. Press two buttons to get settings. press one button 9 times to get to P09. Set P09 to 1. Press one button to advanve to P10. Set P10 to 2. Press two buttons to exit. The whole thing takes about 10 seconds.
P08 is the speed limit and P02 changes the display from KM/h to mph. P14 gives you the chance to increase the power for better hill-climbing. Don't go higher than 18, which is 38% more power than what you presently have. P12 is how much kick you get from the motor at start up. You can turn it down a bit if you feel uncomfortable with the initial kick.