Turn on the unit with the button that looks like a power button (no font for that one).
Press the S key for > 3 seconds, S indicator lights and the F1 parameter appears. Up and down arrow keys cycle through the four parameters. Once you find one you want to change, hold the S key down and use the arrow keys to adjust the value, then press the key that actually looks like a power button to save the value...
F1 = Set Point °C
F2 = Differential °C
F3 = Anti-Short-Cycle Delay
F4 = Probe Offset (aka "calibration")