Two ways of vaping. When you set volts it holds that voltage as long as the mod can with a gradually decreasing battery level by boosting (or decreasing) if necessary. It doesn't take resistance into account, it just delivers that voltage. It will use it to figure the display for the resultant wattage output but not in calculating the voltage. With a wattage setting the mod takes the resistance into account and varies the voltage, boosting (or decreasing) if needed, to whatever is needed to produce the wattage you set. If you change to a different resistance coil it will still manipulate voltage to produce that set wattage. They name it variable voltage but it actually hold's the voltage steady and variable wattage varies voltage to hold the watts steady.