Audio System Issue

[BillW73]

I have a 2013 Limited with the type B sound system. All of a sudden now when I use a phone to play music via bluetooth or AUX, when the song ends it switches over to CDs if there are any loaded, or radio if not. I then have to manually switch it back to Bluetooth or AUX.
Any ideas as to what makes this happen and how to stop it?

Thanks for any ideas,

Bill