Storing connection string

[HardyRexion]

I've been learning all about manipulating databases using VB. DOing well with it but I need to dynamically create a connection string.

I'm almost there, I can populate combo boxes with sq servers and databases and create the correct connection strings

But I'm trying to store the string values and I have this code:

    Private Sub btnGenerateResource_Click(sender As System.Object, e As System.EventArgs) Handles btnGenerateResource.Click

        Dim config As Configuration = _
        ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None)

        Dim csSection As ConnectionStringsSection = config.ConnectionStrings
        csSection.ConnectionStrings.Add(New ConnectionStringSettings("MyConString", txtConnString.Text))
        config.Save()
        ConfigurationManager.RefreshSection("connectionStrings")

    End Sub

All this seems to work but which file is this saved to? I've opened the app.config file and the information isn't stored there. Am I missing something?

[make me rain]

regarding connection string storage i think this link of jmc is fine and simple

secondly connection string must be secured , i mean not physically but as a not human readable script that's it.
to do so what need to be learned to play around on our is , system.encryption a complicated subject ( for me ofcourse )