When launching the universal app from Microsoft Visual Studio 2013 , you can decide to run either the Windows Phone 8.1 project or Windows Store 8.1 app .
How to Change the Start-up Project in Universal App ?
To change the start-up project in Universal App when launching the app locally on Windows 8.1 PC , click the dropdown button that displays “Local Machine” and select Start up project and then select the project that you want to run as shown in the below screenshot.
