Private Sub Worksheet_Change(ByVal Target As Range)
Dim cell As Range
If Not Intersect(Target, Me.Range("A:A")) Is Nothing Then
Application.EnableEvents = False ' Désactiver temporairement les événements pour éviter une boucle infinie
For Each cell In Target
If UCase(cell.Value) = "M" Then
cell.Value = "Marcel"
ElseIf UCase(cell.Value) = "O" Then
cell.Value = "Olivier"
End If
Next cell
Application.EnableEvents = True ' Réactiver les événements
End If
End Sub