Hi,

sorry for responding that late, I had to leave the office earlier
yesterday.

Paste following code into worksheet code module (if you want to see
changes in worksheet MySheet, then paste it into this module):

Private Sub Worksheet_Change(ByVal Target As Range)
Target.Interior.ColorIndex = 6
End Sub

You may change the colorindex (now the value is 6), if yellow is not
your favourite color.

Regards,
Ivan