After creating a Date Slicer, you can customize the calendar.
Day, month, or year view
You can include a third cell in your Slicer Range as the Selection Type, for example, day, month, or year. Valid selections are D for day, M for month, or Y for year.
Day is taken to be the default selection type and is the default display mode if no selection type if specified.
The calendar now displays the month view.
