Carla's Google account has been hacked. She sees things in her Gmail account she doesn't recognize and her YouTube watch list has things on it she never watched. Leo says Google has a security checkup that she can use to see if she's being hacked and she can disconnect any device she doesn't recognize. Carla should also engage 2 Factor Authentication. Obviously, Carla is going to want to change her password as well.
Leo thinks that maybe she accessed her Google account on a public computer and that opening was left there in the form of a cookie. She can check the latest account activity on Gmail through a link at the bottom right of the window.
Leo also suspects that Carla's computer has been compromised and it's not Google at all. She may have malware, like a keystroke logger, that is accessing her account remotely. At that point, he advises she back up her data, wipe the drive and reinstall Windows from a known source.