iPhone almost always defaults to Music app over Spotify Before iOS 7 it seemed like if I had a "music" app open, when I would hit the play button (from the lock screen, ear bud button, bluetooth speakers, etc.) the music from that app would start playing. Now however, it only does that sometimes. For example, last night, I was listening to Spotify on my phone. When I was on my way to work this morning, I hit the bluetooth play button in my car, and it started playing Spotify (exactly what I wanted). Then after I have been to work for about an hour, I plug my ear buds in and hit play, the Apple Music app takes over.

Before I hit the play button, the Spotify app was open and the Music app was closed.

Any idea why this is happening? My phone also randomly restarts from time to time and I am worried that there is something bigger going on with my phone than the Music app just wanting to take over all the time. I would love to know if other people are having this problem or if it's something rare.

My device is an iPhone 5s with the latest version of iOS 7.
It's nothing to do with your iphone it's generally an option on your stereo settings. On my ford fusion, I can select between two apps - Podcasts and Music. I guess it depends on whether your stereo was precisely developed for iPhone or it is generic for any other bluetooth connection.