Как обновить данные из списка и отобразить обновленные данные в списке в VB?

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The form allows me to register customers and save their relevant details into a text file, once I save customers I display this information into a list box. My main aim is now to be able to amend information relative to a customer I have already saved therefore when I select one customer's data from the list box these details are put into numbered text boxes (txtBox1 which is for the customer name and txtBox2 for customer date of birth). I have tried using the code below in (btnUpdate_Click) to only change the parts of data that are amended and avoiding any repetition but it does not seem to work, does anyone got any suggestions? Thank you.

Что я уже пробовал:

Dim strAmendedRecord As String = ""
        For N As Integer = 1 To 5
            Dim txtBoxN As TextBox = Me.Controls.Find("txtBox" & N, True).FirstOrDefault
            If Not IsNothing(txtBoxN) Then
                strAmendedRecord += txtBoxN.Text & (",")
            End If

        Next
        MsgBox(strAmendedRecord)
       
        ListBox1.SelectedIndex = ListBox1.SelectedIndex - 1
        ListBox1.Items.RemoveAt(ListBox1.SelectedIndex - 1)
        ListBox1.Items.Add(ListBox1.SelectedIndex + 1)



        Dim data As String = ""
        For Each item In ListBox1.Items
            data &= item.ToString() & vbNewLine

        Next

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