Apple Music plays song without command.

Hi torian2009,

Thank you for participating in the Apple Support Communities. We understand Apple Music will start playing after watching a movie or YouTube video. If you're playing music in Apple Music and you don't pause the music before you start watching a movie or YouTube video, the music will resume playing after you stop watching videos in the other apps. You may also want to turn off Autoplay which will play similar songs to the previous one. This article explains more about this: Add music to your queue to play next on your iPhone, iPad, iPod touch, or Android device.

"Let Autoplay pick what plays next

Autoplay takes the work out of choosing what to play next. Just play a song, then Autoplay finds similar songs and plays them afterward.

To see your Autoplay queue:

1. Tap the song that's playing at the bottom of your screen.
2. In the lower-right corner of your screen, tap Playing Next .
3. Scroll down to Autoplay. 

To turn Autoplay on or off, tap the Autoplay button  in the upper-right corner of your screen. If you turn off Autoplay on one of your devices, then Autoplay is turned off on any device that's signed in with your Apple ID."

We hope this helps.

Take care.