Honda TRX500FM6 Owner's Manual page 181

Suspension
Position 1: for a light load and smooth terrain.
Position 2: standard position.
Positions 3 to 5: for when the ATV is more heavily loaded. (Also
increase spring pre-load for stiffer suspension.)
Make sure that both shock absorbers are adjusted to the same
position.
Always adjust the shock absorber position in sequence (1-2-3-4-5 or
5-4-3-2-1). Attempting to adjust directly from 1 to 5 or 5 to 1 may
damage the shock absorber.
Servicing Your Honda 171