.net – How to edit application configuration settings? App.config best way to go

For my project I have settings that I added through the Settings in the project properties.

I quickly discovered that editing the app.config file directly seems to no really update the settings value. Seems I have to view the project properties when I make a change and then recompile.

• I'm wondering … what is the best
  and easiest way to handle customizable settings
  for a project — thought this would
  be a no-brainer with how .Net
  handles it … shame on me.

• Is it possible to use one of the
  settings, AppSettings,
  ApplicationSettings, or UserSettings to handle this?

Is it better to just write my settings to custom config file and handle things myself?

Right now … I am looking for the quickest solution!

My environment is C#, .Net 3.5 and Visual Studio 2008.

Update

I am trying to do the following:

    protected override void Save()
    {
        Properties.Settings.Default.EmailDisplayName = this.ddEmailDisplayName.Text;
        Properties.Settings.Default.Save();
    }

Gives me a read-only error when I compile.