You can use the settings infrastructure provided by .NET. In your project's property pages, go to the Settings page, and define your settings. You can define the scope of each setting as "Application" or "User". A class will be automatically generated to access these settings from code.
To access settings Foo and Bar, use :
// Read settings
textBoxFoo.Text = Properties.Settings.Default.Foo;
// Write settings
Properties.Settings.Default.Bar = checkBoxBar.IsChecked;
// Save settings
Properties.Settings.Default.Save();