Accu-Chek COMPACT PLUS User Manual page 22

If you continue to hold down the M button, you then see the following
display after approximately 2 seconds.
mmol/L meter mg/dL meter
or
When you release the M button, your meter is in memory mode. As long
as no results have yet been saved, three bars are displayed.
Press the Test button to turn the meter off.
22
Initial steps before testing