When a crosstab is created in the Report Designer all the row and column groups are summarized automatically.

• In order to turn off the group summary right click on any of the headings in the group and select Delete Row Summary or Delete Column Summary from the context menu.
• Reapply the summary by right-clicking on the heading and selecting the Add Row Summary or Add Column Summary.
• In order to select the summary function and data format for a measure right-click on the measure label and select from the context menu.