YouTube is showing thumbnail of videos on the lock screen. What should I do to fix it?

[Android Central Question]

My brother is experiencing problems with the wallpaper on the lock screen. After he watches a video, the thumbnail shows up on the lock screen, I checked the YouTube tools, and I did not find anything related to this. What should I do to fix it?

 

[djrakowski]

It sounds like YouTube is still running and needs to be closed. Pull down the notification shade and swipe it away, or open the multitasking control and close it.