อยากเปลี่ยน format จาก yyyy/MM/dd เป็น dd/MM/yyyy

For i As Integer = 0 To courow - 1
            dt_Stock.Rows.Add(New Object() {ds.Tables(0).Rows(i).Item("ln_CassetteNo").ToString, _
                                            ds.Tables(0).Rows(i).Item("vc_DrugCd").ToString, _
                                            ds.Tables(0).Rows(i).Item("vc_DrugNm").ToString, _
                                            ds.Tables(0).Rows(i).Item("ln_TheoryStock").ToString, _
                                            ds.Tables(0).Rows(i).Item("vc_LotNo").ToString, _
                                            ds.Tables(0).Rows(i).Item("dt_ValidityDate").ToString("dd/MM/yyyy", Globalization.CultureInfo.CreateSpecificCulture("th-TH"))})
        Next

 DateTime.Parse("***").ToString("dd/MM/yyyy", Globalization.CultureInfo.CreateSpecificCulture("th-TH"))

For i As Integer = 0 To courow - 1
            dt_Stock.Rows.Add(New Object() {ds.Tables(0).Rows(i).Item("ln_CassetteNo").ToString, _
                                            ds.Tables(0).Rows(i).Item("vc_DrugCd").ToString, _
                                            ds.Tables(0).Rows(i).Item("vc_DrugNm").ToString, _
                                            ds.Tables(0).Rows(i).Item("ln_TheoryStock").ToString, _
                                            ds.Tables(0).Rows(i).Item("vc_LotNo").ToString, _
                                            DateTime.Parse(ds.Tables(0).Rows(i).Item("dt_ValidityDate").ToString).ToString("dd/MM/yyyy", Globalization.CultureInfo.CreateSpecificCulture("th-TH"))  })
        Next

CONVERT(VARCHAR(10), dbo.M_Cassette.dt_ValidityDate, 103) AS dt_ValidityDate

dbo.M_Cassette.dt_ValidityDate

dt_Stock.Columns.Clear()
        dt_Stock.Columns.Add("ln_CassetteNo", GetType(String))
        dt_Stock.Columns.Add("vc_DrugCd", GetType(String))
        dt_Stock.Columns.Add("vc_DrugNm", GetType(String))
        dt_Stock.Columns.Add("ln_TheoryStock", GetType(String))
        dt_Stock.Columns.Add("vc_LotNo", GetType(String))
        dt_Stock.Columns.Add("dt_ValidityDate", GetType(String))
        '------------------RP-------------------------
        'dss.Clear()
        ds.Tables().Clear()
        ds = clsP.Stock(0)
        If ds.Tables(0).Rows.Count = 0 Then MsgBox("ไม่มีข้อมูล") : Exit Sub
        dt_Stock.Rows.Clear()
        'MessageBox.Show()
        Dim courow As Integer
        courow = ds.Tables(0).Rows.Count
        For i As Integer = 0 To courow - 1
            dt_Stock.Rows.Add(New Object() {ds.Tables(0).Rows(i).Item("ln_CassetteNo").ToString, _
                                            ds.Tables(0).Rows(i).Item("vc_DrugCd").ToString, _
                                            ds.Tables(0).Rows(i).Item("vc_DrugNm").ToString, _
                                            ds.Tables(0).Rows(i).Item("ln_TheoryStock").ToString, _
                                            ds.Tables(0).Rows(i).Item("vc_LotNo").ToString, _
                                            ds.Tables(0).Rows(i).Item("dt_ValidityDate").ToString})
        Next

        dt_Stock.Columns.Clear()
        dt_Stock.Columns.Add(New DataColumn("ln_CassetteNo", GetType(Long)))
        dt_Stock.Columns.Add(New DataColumn("vc_DrugCd", GetType(String)))
        dt_Stock.Columns.Add(New DataColumn("vc_DrugNm", GetType(String)))
        dt_Stock.Columns.Add(New DataColumn("ln_TheoryStock", GetType(Long)))
        dt_Stock.Columns.Add(New DataColumn("vc_LotNo", GetType(String)))
        dt_Stock.Columns.Add(New DataColumn("vc_ValidityDate", GetType(String)))

        '------------------RP-------------------------
        'dss.Clear()
        ds.Tables().Clear()
        ds = clsP.Stock(0)

        If ds.Tables(0).Rows.Count = 0 Then MsgBox("ไม่มีข้อมูล") : Exit Sub
        dt_Stock.Rows.Clear()
        'MessageBox.Show()

        ds.Tables(0).Rows.Cast(Of DataRow)().ToList().ForEach(Sub(dr)
                                                                  Dim drNew = dt_Stock.NewRow()
                                                                  drNew("ln_CassetteNo") = dr.Field(Of Long)("ln_CassetteNo")
                                                                  drNew("vc_DrugCd") = dr.Field(Of String)("vc_DrugCd")
                                                                  drNew("vc_DrugNm") = dr.Field(Of String)("vc_DrugNm")
                                                                  drNew("ln_TheoryStock") = dr.Field(Of Long)("ln_TheoryStock")
                                                                  drNew("vc_LotNo") = dr.Field(Of String)("vc_LotNo")
                                                                  drNew("vc_ValidityDate") = dr.Field(Of DateTime)("dt_ValidityDate").ToString("dd/MM/yyyy", New System.Globalization.CultureInfo("th-TH"))
                                                                  dt_Stock.Rows.Add(drNew)
                                                              End Sub)

Dim dt_Stock As DataTable() = ds.Tables(0).Clone()
ds.Tables(0).AsEnumerable().ForEach(Sub(r)
                                        dt_Stock.Rows.Add(r.ItemArray())
                                    End Sub)
'Set Culture
System.Threading.Thread.CurrentThread.CurrentCulture = System.Globalization.CultureInfo.CreateSpecificCulture("th-TH")
dt_Stock.Locale = System.Threading.Thread.CurrentThread.CurrentCulture
...
...
...
'Reset Culture
System.Threading.Thread.CurrentThread.CurrentCulture = System.Globalization.CultureInfo.CreateSpecificCulture("en-US")
dt_Stock.Locale = System.Threading.Thread.CurrentThread.CurrentCulture