It shows temperature in Fahrenheit. I struggle to switch it to Celcius

To change between F & C please follow these steps:
Press and Hold the Multi Function Button for 2sec (Auto Function Check should appear 188.8) ---> Press and Hold the Multi Function Button for 2sec again (last recorded Temp should show) ---> Press and Hold the Multi Function Button for 3sec and the temp scale (F or C) will be flashing. ---> Press the Multi Function button once to toggle between the two. You should hear a beep and the (F or C) will stop flashing and it is ready for use. I hope this helps. Thank you for asking.