Before pedalling off it is a good idea to take a moment to make sure that you have set the pedal length position appropriately for your leg length. Leg length adjustments are made by locating the length adjustment pin into whichever setting hole provides a comfortable pedal stroke for the user.
This is done by gripping the length adjustment actuator (on the pedal crank) so that the locator pin is released from it's current position and then moving the crank left or right and then relocating the pin into whichever hole you want to set it into.
Make sure that the pin is fully positioned into the hole correctly, like so.
The numbers on the top of the drum are there to indicate leg length, as pictured below. Unless you have one leg significantly shorter than the other, you will need both left and right locator pins on the same setting.
Experiment with leg length settings until pedal strokes feel comfortable and natural. You want to avoid a cramped pedaling style (adjustment too short) and you also want to avoid having to out-stretch and hyper-extending your legs (adjustment too long). As a rule of thumb, if you are feeling the pedals reach the end of the stroke without extending your legs fully, the length is too short. If you are unable to reach the full extension by fully extending your legs, it's probably set too long.