Used only when a custom group is on the report, this subcategory allows you to choose whether you would like to use the default setting or whether to allow subtotals. Click in the cell under Allow Subtotals to select your preference. To specify that all the custom groups use the default setting, click Reset all.
When default is used, the object inherits the property set in the Custom Group Editor. That setting in the editor is inherited, by default, for any report that uses that custom group.