Follow the recipe, or just use whatever setting produces the result you need. It's hard to say what setting because it depends on your particular stove, how much is in the pan and what you're trying to do - fry, boil, simmer, whatever. Really you need to work it out from experience with your stove.
For example, if you want to get something boiling, you need the highest setting or you'll be waiting too long, though you can often turn it down a bit once it's boiled just to keep it on the boil. If I have instructions such as "bring to the boil and simmer for 30 minutes", then once it's bubbling, often I can turn it right down to the lowest heat and that's enough to keep it on a gently bubbling simmer. Especially with the lid on. Or maybe the second lowest if it's a big panful such as a big pot of stew.
You'll need a higher heat for frying, though if you have bubbling hot fat that splashes out of the pan, maybe that's too much! I tend to find that a medium heat will do for something like frying chopped onions for 5 minutes until soft (which I mention because I find myself doing that a lot!)
It would help to see someone make the dish so you can see what it's supposed to look like at the various stages of making it, then you can copy and get used to how to achieve that on YOUR stove.