Perhaps you should look at adding a Settings File. (e.g. App.Settings) Creating this file will allow you to do the following:
string mysetting = App.Default.MySetting;
App.Default.MySetting = "my new setting";
This means you can edit and then change items, where the items are strongly typed, and best of all... you don't have to touch any xml before you deploy!
The result is a Application or User contextual setting.
Have a look in the "add new item" menu for the setting file.