Variable voltage allows you to change the temperature of the heating coil. This can affect the flavor of your juice, the temperature of your vape, the amount of vapor and to an extent the perceived throat hit.
There's several ways to set your voltage, but in the end you'll learn over time what works best for you.
The simplest way is to measure the resistance (ohm rating) with your Provari. It has a built-in ohm meter. Whatever the measurement is, take that and add the number "2". ( 2.0 ohm + 2 = 4 volts). Start out using 4 volts on your Provari, and adjust up or down to adjust to the best flavor or vapor temperature you prefer.
I happen to prefer a cooler vape as opposed to a warmer one, so I very rarely go above 4.5 volts on my Provari's. I generally choose coil resistances 2.5 - 3.0 ohm when purchasing my juice attachments, as that resistance will have the widest range of options in voltage for the Provari. The below
Safe Vaping Power Chart is an easy way to visualize what is known as Ohms Law. It is a general guideline used to show the relationship between ohms, voltage, and wattage.
You will likely find that each flavor will have it's "sweet spot" in the voltage it likes for fullest flavor. I find that fruit flavors are best in the lower voltage range. Something like a coffee or tobacco flavor is better in the mid to upper ranges. Experiment with the flavors that YOU use to find their sweet spot on your setup.