Read original post by Nick Randolph at Visual Studio Magazine
In my "Storing Windows Phone User Settings" column, I showed you how to persist settings for your Windows Phone application via the IsolatedStorageSettings class. The limitation with this implementation, however, is that when users switch phones, or reinstall the application, they will lose those settings.
To address these issues, I'll show you how to save the settings to the cloud and retrieve them. At this point, there's a choice to be made regarding the cloud storage you use. One option is that you supply the nominal amount of storage required to store the settings for each user of your application. This typically involves a small initial cost for cloud storage, but it could escalate based on the success of your application.