Hold MENU, and select Settings > System > Time.

Time Format

Sets the device to show time in a 12-hour or 24-hour format.

Set Time

Sets the time zone for the device. The Auto option sets the time zone automatically based on your GPS position.

Time

Allows you to adjust the time if it is set to the Manual option.

Alerts

Allows you to set sunrise and sunset alerts to sound a specific number of minutes or hours before the actual sunrise or sunset occurs.

Sync With GPS

Allows you to manually sync the time with GPS when you change time zones, and to update for daylight saving time.