Clarity XLC8 User Manual page 33

MENU - DATE & TIME
In standby mode, press MENU. Press UP or DOWN arrow to advance the row
that reads "Date & Time". Press MENU to enter the date and time setup.
Use the numeric keypad to enter the date (follow format on screen). Press
MENU to save your selection. Use the numeric keypad to enter the time
(follow format on screen).
Press MENU to save your selection. The screen will display "OK" and you
will hear five beeps.