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.