Editing a Calculated Field Definition

You can edit a calculated field to change its name, type, data length, column width, decimal accuracy, or expression.

Select Formula Field, Lookup Fields, Runtime Parameter Fields, or User Edit Fields on the Table Design ribbon.
The calculated fields are displayed on their own window. Select the field you wish to edit on the selector.
Make the desired changes to the definition, and then choose Accept to update the field. Otherwise, choose Cancel to exit the dialog without making changes.