Bonjour MATE & bienvenue,
à tester,
Merci Theze, c'est corrigé
Sub test()
Dim ancien, nouveau
Dim Wk As Workbook, f As Worksheet, i As Integer
Dim FD As FileDialog
ancien = Array("TTTTTTT", "VVVVVV")
nouveau = Array("B4566U", "TUH67J")
Set FD = Application.FileDialog(msoFileDialogFilePicker)
FD.AllowMultiSelect = True
FD.Filters.Clear
FD.Filters.Add Description:="Excel Files", Extensions:="*.xls;*.xlsx"
FD.Show
If FD.SelectedItems.Count > 0 Then
For i = 1 To FD.SelectedItems.Count
Application.Workbooks.Open FD.SelectedItems(i)
For Each f In Workbooks(FD.SelectedItems(i)).Worksheets
For j = LBound(ancien) To UBound(ancien)
f.Cells.Replace What:=ancien(j), Replacement:=nouveau(j), LookAt:=xlPart, _
SearchOrder:=xlByRows, MatchCase:=False, SearchFormat:=False, ReplaceFormat:=False
Next j
Next f
Workbooks(FD.SelectedItems(i)).Close Save
Next i
End If
End Sub