Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)
If Not TypeOf Sh Is Worksheet Then Exit Sub
Sh.Unprotect
Application.EnableEvents = False
With Target.Offset(0, 1)
.Value = Now: .NumberFormat = "yyyy/mm/dd hh:mm:ss": End With
Application.EnableEvents = True
Sh.Protect
End Sub