A random phone connects to my Spotify

[shibaku]

Someone keeps randomly connecting to my spotify with his phone and i have no control over blocking it. Sometimes his music just randomly starts playing on my phone or PS4. 

How do i block this? its annoying as hell. i can't even listen to my music like this.

[user-removed]

Start with going to your account https://www.spotify.com/account/overview/

At the bottom of the page, hit Sign out everywhere. After that I recommend you to change your password