How to Change the Calendar Region on a Mac

Displaying Alternate Calendars

1. 
   Click the Calendar app. You'll find this in your Dock. You Calendar app can display an alternate calendar alongside your regular one.
2. 
   Click the "Calendar" menu. This appears when the Calendar app is the active window.
3. 
   Click "Preferences."
4. 
   Click the "Show alternate calendar" box. This is at the bottom of the "General" tab.
5. 
   Click the menu to view the alternate calendars.
6. 
   Click the alternate calendar that you want to use. This will add that calendar's numbering system to the upper-left corner of each day in the Calendar app.