Playlist get deleted, new ones get added and random people use my account

[Insane36]

So I heard after logging out of all device and changing the Password, logged in via Facebook Account, it should fix the problem. Unfortunatly this still happens and I have no idea how to adress this topic furthermore. 

Please help.

[Blackstone30]

Yeah i suddenly have this problem too...and it shows me at "Connected Devices" suddenly a foreign Smartphone...i never seen before....Each time i wanna listen to my music it switches to that Moto G (4) Smartphone...