Hi,

What you are entering is called event code and the event
Private Sub Worksheet_Change...
is executed whenver the worksheet changes but you can only have one module
with this name. You could try something like this

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address = "$A$1" Then
      'do something
End If

If Target.Address = "$B$1" Then
      'do something else
End If
End Sub

Mike