Your Shorts are open to remixing by default. Here is the YouTube Studio setting that limits it, and what YouTube Help says happens to remixes already made from your video.
What YouTube says you must disclose, what you can skip, where the label appears and when YouTube adds one for you.
Who can use YouTube's built-in thumbnail and title test, how to set it up, and how to read Winner, Performed Same and Inconclusive.
YouTube's own hashtag limits, and a sensible number to use.
Chapters come from your description timestamps; three rules decide if they show.
The current thumbnail specs from YouTube Help, without the guesswork.
YouTube says half of all channels and videos have an impressions click-through rate between 2% and 10%, and its own A/B tests now pick winners by watch time, not clicks. What YouTube says, where feed previews and Shorts reduce the thumbnail's role, what testing shows about style, and how to decide how much effort to spend.
In 2008, YouTube stopped offering thumbnails from the 25, 50 and 75 percent marks of a video and let partners upload their own. What followed was YouTube Face: why faces took over, why they looked shocked, how A/B testing pushed even MrBeast to close his mouth, and five lessons for your own videos.