Someone in another country is using my account

So I have been having an issue a while. I keep getting messages where someone is using my account. There is my husband, myself and daughter in our family account.  When I'm listening my music changes to some heavey metal music and mine stops. I have found music not mine in my tracks and albums. This is constant issue. I have uninstalled and reinstalled  it's happening to me and my husband. How do I stop this.  I have just attempted to change the password and it say an error has occurred. I don't know how to get rid off the devices on there. Also how do I remove this musica from my personal play list. I oy want the one that says car.