title: ConfigurationManager doesn't save settings
body: <p>Here is the code I'm using:</p>
  
  <pre><code>private void SaveConfiguration()
  {
      if (txtUsername.Text != "" &amp;&amp; txtPassword.Text != "")
      {
          ConfigurationManager.AppSettings["Username"] = txtUsername.Text;
          ConfigurationManager.AppSettings["Password"] = txtPassword.Text;
  
          MessageBox.Show("Su configuracion guardo exitosamente.", "Exito!");
          this.Close();
      }
      else
      {
          MessageBox.Show("Por favor lleno los campos.", "Error.");
      }
  }
  </code></pre>
  
  <p>Now, the settings are persisted but when I close the application and press F5 to run it again, the values are reverted to what is typed into the app.config file. Any suggestions?</p>