2008 GMC Yukon Owner's Manual - Page 258

Changing the Time and Date Default Settings To change the time default setting from 12 hour to 24 hour or to change the date default setting from month/day/year to day/month/year, follow these instructions: 1. Press the MENU button. Once the H option displays, press the pushbutton located under the forward arrow that is currently displayed on the radio screen until the 12H (hour) and 24H (hour), and the date MM/DD (month and day) and DD/MM (day and month) displays. 2. Press the pushbutton located under the desired option. 3. Press the MENU button again to apply the selected default, or let the screen time out. Radio(s) (MP3) Radio with CD shown, Radio with Six-Disc CD similar 3-84