Both the daily detail screen and the monthly detail screen have the Preferences button in the upper right. Here you can set the time format, first day of the week, number of events to show in the calendar block, days to look forward for events and if the filters on this calendar should be saved as the default for all calendars.
Site administration settings
The following settings can be changed by a site administrator in Administration > Appearance > Calendar:
Admins see all
Whether admins see all calendar events or just those that apply to themselves.
Time display format
Whether a 12 or 24 hour format is used. This setting can be overridden by user preferences.
Start of week
Default is Sunday.
Weekend days are shown in a different colour.
Days and events to look ahead
For determining how many events are listed in the Upcoming Events block. If the Upcoming Events block becomes too long you can reduce the number of days and events to lookahead.
Calendar export days to look ahead and back
in Moodle 2.5! In Moodle 2.5 onwards, a custom range of dates, such as a school term or year, may be set as a calendar export option.
Calendar export salt
The calendar export salt is a random string of characters used for improving of security of authentication tokens used for exporting of calendars.
The Calendar editor role may be used to enable users to add course or site events to the calendar.