It is kind of counter intuitive, but I got 'er done.If you want more explanation of the calibration procedure, just let me know and I will go through the steps. It's a bit counter-intuitive, for me anyway.
Built in therm was about a degree off, it is now spot on.
Am much more comfortable with this thing now that I know how to get it into 'change' mode, thanks to EEF's precise instructions.