To change the temperature unit from Celsius to Fahrenheit on the iProven NCT-978 Infrared Forehead Thermometer, follow these steps:
1. Make sure the thermometer is turned on and in the measurement mode.
2. Press and hold the SET button until the display shows "F1".
3. Press the MODE button to switch between Celsius and Fahrenheit.
4. Press the SET button to confirm the unit setting.
5. The thermometer will now display temperature readings in the selected unit.
Please refer to the "Parameter settings" section of the instruction manual for more information on adjusting the temperature unit and other settings.