Begin by pressing and holding the SET button.  Next press and hold the PROG/MAN button.  Release both buttons.  The current time of day will appear on the display.  Set the clock to the correct time by pressing either the down or up buttons.  When the correct time is set press and release the SET button.  The day of the week will be displayed.  Press either the down or up buttons to display the correct day of the week.  Press and release the SET button to select the correct day of the week.  The differential setting will be displayed.  Press either down or up buttons to select the preferred setting of .5, 1.0, 1.5, or 2.0 degrees.  Press and release the SET button or wait 45 seconds and the display will return to its normal mode.