Accu-Chek Compact Plus Reference Manual page 27

After you have turned on the alarm clock function, you need to set the
times. You can set up to three different times.
However, you do not have to set all three alarm times.
If you choose to enter only one or two times,

press the Test button to turn the meter off once you have entered
the time(s) and the hour for the next time is flashing,
or

press the S button repeatedly until you reach the hypo indicator
setting (see Chapter 3.7 "Setting the hypo indicator".
Press the S button.

The display shows a 1 and, at top left, the first time at which you
wish to receive the alarm call. The presetting is 0:00 (24-hour for-
mat) or 12:00 a.m. (12-hour format). The hour flashes in the display.
50
Press the M button repeatedly until the correct hour is displayed.

The meter increments the hours.
24-hour
format
12-hour
format
24-hour format: If you hold the M button down, the meter fast-scrolls
forward to 23, and then starts again at 0.
12-hour format: If you hold the M button down, the meter fast-scrolls
forward to 12 p.m. and then to 12 a.m.
Settings Settings
M
M
51
3