First of all I would read the owner’s manual that came with the grill. Each grill is different. I have found over the years that is the first thing to do when buying a new appliance. It will give you lots of helpful hints and tips for working with your particular model.
Some people make the mistake of cooking everything on high and your manual should address this. Some things have to be cooked on high but I checked out the temperature of my grill with an oven thermometer and here is what I discovered:
Low is about 350 or so degrees
Medium is about 400 to 500
High is about 550 to 600 or 700 degrees.