conversion format date en texte en conservant un format de date

Sub Traitement()

 Dim derligne As Long
 Dim x As Range 'cellule affichant le coefficient multiplicateur 100
 Dim taille As Range '1ère ligne contenant le symbole % dans les en-tête
 Dim colonne As Integer 'n° de la colonne à modifier
 Dim lignefin As Integer 'n° de la dernière ligne
 Dim ws As Worksheet
 
 On Error Resume Next 'si la feuille n'existe pas !
 Application.DisplayAlerts = False: Sheets("traitement").Delete: Application.DisplayAlerts = True
 On Error GoTo 0 'plus de gestionnaire d'erreurs
 Worksheets("PO - PB").Copy After:=Worksheets("base donnee") 'création de la feuille
 ActiveSheet.Name = "traitement" 'nom de la feuille'
 Sheets("base donnee").Range("A1:DX1").Copy Sheets("traitement").Range("A1:DX1")
 ActiveSheet.AutoFilterMode = False 'desactiver les filtres'
 ActiveWindow.FreezePanes = False 'désactiver les volets'
 ligne = Range("A" & Rows.Count).End(xlUp).Row
 colomne = Cells(1, Cells.Columns.Count).End(xlToLeft).Column
 With Sheets("traitement")
      Set x = Range("A" & ligne + 10)
           x.Value = 100
           
          Set taille = .Range("A2:DX100")
          For Each cell In taille
          
              If cell.HasFormula = True Then
              cell.EntireColumn.Rows("2:775").Select
              selection.Copy
              selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone
          
          
              [b]'detecter date et la mettre en texte + bon format
              ElseIf IsDate(cell) Then
              cell.EntireColumn.Rows("2:761").Select
              selection.NumberFormat = "@"
              selection.NumberFormat = "yyyy-mm-dd"[/b]
                            
             ElseIf InStr(1, cell.Text, "€") > 0 Then
              cell.EntireColumn.Rows("2:761").Select
              selection.NumberFormat = "0.00"  'pour 2 décimales
              selection.Copy
              selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone

             ElseIf InStr(1, cell.Text, "%") > 0 Then
               colonne = cell.Column
               lignefin = cell.End(xlDown).Row
               x.Copy
               Range(Cells(1, colonne), Cells(lignefin, colonne)).PasteSpecial _
               Paste:=xlPasteValues, Operation:=xlMultiply, SkipBlanks:=True
                   For i = 2 To lignefin
                     If CStr(Cells(i, colonne)) = "Erreur 2015" Then Cells(i, colonne) = ""
                   Next i
               selection.NumberFormat = "0.00"
               selection.Copy
              selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone
            
             End If
            Next
     End With
     
  ActiveSheet.UsedRange.Replace What:="/", Replacement:="", LookAt:=xlWhole
  ActiveSheet.UsedRange.Replace What:="#REF!", Replacement:="", LookAt:=xlWhole
  ActiveSheet.UsedRange.Replace What:="#VALEUR!", Replacement:="", LookAt:=xlWhole
  
         'For Each ws In Worksheets
         'Application.DisplayAlerts = False
         'If ws.Name <> "traitement" Then ws.Delete
         'Next
          'Application.DisplayAlerts = True
     
'ActiveWorkbook.SaveAs Filename:="Traitement", FileFormat:=xlCSV, CreateBackup:=False, local:=True

 End Sub