Edit a calculated field

In the design window, make sure the PivotTable list is activated. For instructions, see Help for your design program.
Select the calculated field whose expression you want to edit.
On the toolbar, click Commands and Options , and then click the Calculation tab.
Edit the expression, and then click Change.
The data values will be automatically recalculated using the new expression.

To add field references, select a field that you want to use from the Insert Reference to drop-down box, and then click the Insert Reference To button.