Bonjour Steph47,
A tester :
Private Sub CommandButton2_Click()
Sheets("Annexe").Select
Dim i As Integer
i = Sheets("Annexe").Range("a65536").End(xlUp).Row + 4
' cellules A, B, C, D à fusionner et centrer
Range(Cells(i, 1), Cells(i, 4)).Merge
Range("A" & i).Value = TextBox1
Range("A" & i).Font.Bold = True
Range("A" & i).HorizontalAlignment = xlCenter
Range(Cells(i, 1), Cells(i, 4)).BorderAround LineStyle:=xlContinuous
Me.TextBox1 = ""
Unload Me
End Sub