First, you can only be in one setting at a time as variable volts and variable watts are essentially the same thing. With variable volts, or the U setting on the MVP, you are manually adjusting the volts to taste. If it isn't enough of a hit, you go up to the next volt setting and so on. With variable watts, you are still adjusting the volts. The thing is, once you find the hit you like, you can leave it there and the
device will adjust the volts on it's own, depending on the resistance of the coil you are using. Basically, its a set it and forget it mode. If you set it at 10 watts with a 1.5 ohm coil, and then switch to a 2.0 ohm coil, it'll increase the voltage on it's own to get to 10 watts again. That's what watts is. A calculation between ohms and volts.
So, if you aren't getting a good enough hit at 10 watts, or 10 P keep going up until you find what you like. As long as you stay in P mode, or watts mode, it'll just give you that same hit like no matter what
tank or coil you switch to.