You can configure a report to let users adjust its grouping and stacking.
Configure alternative Group by and Stacked
by choices that users can select when viewing the chart. Additional
group bys can be added to any report that supports group bys (such as bar or pie)
and to list reports as columns. When you configure an additional group by to a bar
or horizontal bar, it is also added as an additional stack by. You can add variables
and variable groups as additional group bys.
Note: Additional Group by values you select also appear in the
Stack by choice list. As a result, date/time fields may
appear in the Stack by choice list in generated reports.
However, if you stack by a date/time field in a generated report, an error