Redmi Pro Music Randomly Starts In The Pocket

[dntpw]

Hello,
I recently bought about 3 months ago a Redmi Pro in China, running on the latest MIU 8.
The music randomly starts when the cellphone is in my pocket.
I have changed the music player to phonograph, however if I turn off the device it always chose the Xiaomi music player.
How to solve this problem?

Thanks

dntpw