Several settings in Settings > Mail, Contacts, Calendars affect Calendar and your calendar accounts. These include:

  • Syncing of past events (future events are always synced)

  • Display of events found in Mail messages

  • Default calendar for new events

  • Default time for alerts

  • Time zone override, to show dates and times using a different time zone

  • Which day starts the week

  • Display of week numbers in the monthly calendar

  • Display of Chinese, Hebrew, or Islamic dates