Option Explicit
Public rngFF As Word.Range
Public fldFF As Word.FormField

Public Sub DropDownColour()
Dim bProtected As Boolean
    With GetCurrentFF
        If .Type = wdFieldFormDropDown Then
            'Unprotect the file
            If ActiveDocument.ProtectionType <> wdNoProtection Then
                bProtected = True
                ActiveDocument.Unprotect Password:=""
            End If

            Select Case .Result
                Case "A": .Range.Font.ColorIndex = wdRed
                Case "B": .Range.Font.ColorIndex = wdYellow
                Case "C": .Range.Font.ColorIndex = wdGreen
                Case Else
            End Select
            'Reprotect the document.
            If bProtected = True Then
                ActiveDocument.Protect _
                        Type:=wdAllowOnlyFormFields, _
                        NoReset:=True, _
                        Password:=""
            End If
        End If
    End With
lbl_Exit:
    Exit Sub
End Sub

Public Function GetCurrentFF() As Word.FormField
    Set rngFF = Selection.Range
    rngFF.Expand wdParagraph
    For Each fldFF In rngFF.FormFields
        Set GetCurrentFF = fldFF
        Exit For
    Next fldFF
lbl_Exit:
    Exit Function
End Function