If you live in the U.S., the NC° Thermometer Gen1 is pre-programmed to Fahrenheit units. If you would like to switch to measuring in Celsius (or back again), you can press and hold the power button when the thermometer is turned off to change units.
You can also find more information about this in the instructions for the thermometer.
If you do not live in the U.S., the NC° Thermometer Gen1 doesn’t have the option to switch units. You will receive a Celsius thermometer or a Fahrenheit thermometer depending on the preferred unit you selected when you signed up.
To change the temperature unit used in the app, go to the menu in the top left corner > Settings > Units. When you make this switch, it will automatically convert all of your added temperatures to the desired temperature unit.