Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Row <> 2 Then Exit Sub
Me.Protect DrawingObjects:=True, Contents:=True, Scenarios:=True, _
Password:="xxx", UserInterfaceOnly:=True
Intersect(Target.MergeArea.EntireColumn, [3:100000], _
UsedRange).Locked = Target.Value = "Réalisé"
End Sub