You can change the temperature units on the NC° Thermometer Gen3 from Fahrenheit to Celcius and vice versa.
This can be done by going to the menu in the top left corner of the app > My device > Device settings > Units. The new setting will be applied once you have connected the thermometer with the app while on the My device page.
Alternatively, you are also able to change the units on the thermometer without connecting to the app, by pressing the Settings button for five seconds while the thermometer is turned off.
However, please note that if you have your thermometer and app set to different temperature units, the thermometer’s units will be updated to match the app the next time you connect it with the app.