Volvo VNL Operator's Manual page 230

Clock Function
Setting Clock
Press in the "SET" button for 3 seconds and the hour digits will start to flash.
Set the hour by pressing the up or down arrow button. The time can either
be set as an AM-PM or 24-hour mode. To go from the 24-hour mode to the
AM-PM mode, continue to press one of the arrow buttons until the new
mode is shown.
Accept the hour by pressing the "SET" button. The minute digits will now
start to flash.
Set the minute by pressing the up or down arrow button.
Accept the minute by pressing the "SET" button. The clock is now set.
Cab Interior and Sleeper 225