In Default options section, the administrator can define default settings for all new users. Users can override those settings.
Note that the default all-day event hours can be taken from Jira Time Tracking settings.
The long event display means the display for the events that are either equal to all-day events or longer than them. Based on your preferences, you can adjust the display for long events either on a time grid or in the all-day section of a calendar.
By default event minutes is meant the event’s duration in case it is based on a single date-time picker.
In Global options section, as admin, you can define who is going to be an event organizer for the events that are exported outside the Company Calendar Planner, the reporter, or the assignee.