On mine, it's located in the middle of the clock setting page.
the touch manual says...
Setting the clock
1. Press MENU > Clock.
2. Press + and — to adjust the time.
From this screen, you can also
access other adjustments such as 12
or 24 hour mode, to activate GPS
time synchronization, and to have
the system automatically update
new time zones.
Once you update any settings they will be automatically saved.
Note: The date will be set by your vehicle’s GPS. You cannot manually
set the date.
Note: After a battery disconnect, your vehicle will need to acquire a GPS
signal to update the clock. A GPS signal can be received in an open sky
area. Once your vehicle acquires the signal, it may take a few minutes
for the update to display the correct time.