YouTube’s help pages describe recommendations as a matching problem: your habits are compared with habits that look similar, then the system suggests videos those people also found useful. It is not a single secret recipe. The company says the system learns from more than 80 billion signals.
Watch history is the heavy signal on the homepage. Search history, subscriptions, likes, and survey answers about whether a video was satisfying also matter. If you pause or delete watch history, the homepage has less personal material to work with.
Up Next is more about the video on screen. The clip you are already watching is the main clue for what should play afterward, mixed with a guess about your wider taste. That is why a cooking tutorial can lead to another recipe, then slowly drift toward travel food.
You still have controls. You can tell the site you are not interested, remove a video from history, or turn history off. Recommendations get quieter when you give them less to learn from—and louder when you binge one topic.
The practical takeaway is simple. If the homepage feels stuck, it is often repeating a recent streak. A few “not interested” taps, or watching something you actually want, usually steers the next row more than any rumor about a hidden trick.