You sure can.
From contacts or calendar view, press MENU, then touch Preferences.
Here you can:
- Change the default contact and calendar views.
- Change your background "theme" color and text size for your display.
- Modify the Sync Interval between the mobile device and the ClearSync server. 5 minutes is default.
TIP If you don't need to sync to the server every 5 minutes, increase this interval and save on battery life.
- Change from AM/PM time display to 24 hour display.