Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Cells = 1 Then
If Target.Column = 1 Then
Rem code for column A
ElseIf Target.Column = 3 Then
Rem code for column B
End If
End If
End Sub
Private Sub Worksheet_Change(ByVal Target As Range)
Rem one routine
Rem the other
End Sub