Depending on where it is to be sold, your thermometer leaves the factory preset to: Celsius (°C) or Fahrenheit (°F). These settings can be modified as follows:
When the thermometer is in stand-by mode, press and hold the “mem” button (or “face” or “on” button in the older models); after about 8 seconds, the visualization on the display changes showing the settings in sequence: °C, °F, AXILLA, ORAL, RECTAL. When the preferred setting appears, release the button. After a few seconds, the thermometer will be ready for a measurement in the selected setting.