Private Sub Worksheet_Change(ByVal Target As Range)
Application.EnableEvents = False 'désactive les évènements
If Target.Address = "$A$1" Then [A2] = IIf([A1] = "", "", Application.Proper(Format(Date, "dddd")))
If Target.Address = "$A$2" Then [A1:A2] = ""
Application.EnableEvents = True 'réactive les évènements
End Sub