If you opt to stick with the ActiveX controls (which I don't recommend) and if the option buttons are in fact captioned "Yes", "No" and "NA" then:
Code:
Sub ScratchMacro()
'A basic Word macro coded by Greg Maxey
Dim oFld As Field
For Each oFld In ThisDocument.Fields
Select Case oFld.OLEFormat.ClassType
Case Is = "Forms.OptionButton.1"
If oFld.OLEFormat.Object.Caption = "No" Then oFld.OLEFormat.Object.Value = True
End Select
Next
lbl_Exit:
Exit Sub
End Sub