Change the master calendar title
Each master calendar has a title, which is displayed in the calendar header. The calendar title can be changed by the calendar administrator:
The Identity section is also where you can customize the calendar header. Details here.
You can use calendar parameters to display and print a calendar with a custom title.
Change sub-calendar names
Each sub-calendar also has a title. When the calendar administrator creates a sub-calendar, they enter a name for it. Sub-calendar names can be changed at any time:
More about how to configure sub-calendars.
Note that sub-calendar names are also used to create folder hierarchies. Details here.