I have had suspicious Youtube watch history for months now, and it's finally starting to worry me. I'd like to keep my Youtube activity private, and these random strings of videos I find in my history leads me to believe that someone is logged into my account from another computer or mobile device--likely one I used in the past. Most of the videos that are being watched suggest someone that is at least my father's age, or older... and if it's an older family member, I'd rather them not have the ability to view my watch history, for obvious reasons.
I spent hours trying to solve this problem on my own, using search engines for a solution and surfing the massive Google+ and Youtube interface. All of the solutions I found via google search were years old, they all mentioned the same "sign out of all other sessions" option in gmail and youtube, and both sites no longer seem to have this option (at least to my discovery). The customer service telephone number failed me for a solution as well, as did the support section of google.com; and, the user activity section in gmail showed that no other IPs had logged into my account, but I'm not sure if that even means anything since it's youtube on which I have suspicious activity. I have literally exhausted myself trying to come up with an answer, so if anyone knows a way that I can kick all devices off of my account, I would be greatly appreciative. Thank you.