I have these pieces of code:

```
string theme = ConfigurationManager.AppSettings["Theme"];

private void ChangeTheme(string Name)
    {
        if(Name=="Light")
        {
            Form1.ActiveForm.BackColor = System.Drawing.Color.White;
            Form.ActiveForm.ForeColor = System.Drawing.Color.Black;
        }
        if (Name == "Dark")
        {
            Form1.ActiveForm.BackColor = System.Drawing.Color.Black;
            Form.ActiveForm.ForeColor = System.Drawing.Color.DarkOrange;
        }
        Configuration cfg = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
        cfg.AppSettings.Settings["Theme"].Value = Name;
        cfg.Save(ConfigurationSaveMode.Modified);
        ConfigurationManager.RefreshSection("appSettings");
    }

```

My app.config:

```
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key="Volume" value="7"/>
    <add key="Keyval" value="X"/>
    <add key="Theme" value="Light"/>
  </appSettings>
</configuration>

```

Basically, when I press the radio buttons it changes the theme and sends the string to changetheme(), but it does not update in the app.config.