one way:
Put this in the ThisWorkbook code module (right-click on the
workbook title bar, choose View Code, paste the following in the
window that opens, then click the XL icon on the toolbar to return
to XL):
Private Sub Workbook_Activate()
Application.AutoCorrect.AddReplacement "(a)", "(apple)"
End Sub
Private Sub Workbook_Deactivate()
Application.AutoCorrect.DeleteReplacement "(a)"
End Sub