The whole point in owning a variable volt / watt power device is the ability to vary power output to the delivery device using a wide variety of coil resistances, air flow, pg/vg ratios, flavors, etc. .
There is no right / wrong / best / optimal power setting it is a matter of personal preference. Some flavors will taste best at a higher or lower power setting than others.
Folks get way too hung up on the numbers & over complicate stuff that is simple.
Pick volt or watt mode, most seem to prefer watts, start off at a low power setting & slowly increase power taking a vape or three on each setting until you find what you like in vape quality. If you get an odd off funky or burnt taste, turn it down.