Press both the up and down arrows simultaneously for 3 seconds and let go. You will see F for Fahrenheit or C for Celcius. Press the light button or wait 5 seconds and the screen will change to the first stage differential. Use the arrows to adjust between 1-3 in .5 degree increments. Press the light button or wait 5 seconds and the screen will change to the second stage differential. It is adjustable from 1-6 in .5 degree increments. Press the light button or wait 5 seconds and you will see the second stage delay. It is adjustable from 10-40 minutes in 5 minute increments. When you are done leave the thermostat and it will return to the main screen in 10-15 seconds.