Simply long press the fire button and "+" regulate button simultaneously to enter into the regulation interface. Then press the "+" button again to enter into Preheat Setting Menu. (When you enter into the preheat menu, press the "-" button first then to regulate the preheat power and duration.) Press the fire button to switch between preheat power and preheat duration. Press "+" or "-" buttons to regulate. Long press the fire button to confirm.