Different surfaces, different rules
Feed, Stories, Reels and Explore each use their own ranking. The feed favors accounts people interact with, while Reels and Explore lean on predicted interest from people who do not follow you yet.
The signals that matter
Watch time, shares, saves and comments are the strongest indicators. A share to a direct message tells the system your content is worth spreading, which is why it often triggers wider distribution.
Practical takeaways
Hook viewers in the first second, keep videos tight, write captions that invite a response and post when your audience is active. Test one change at a time so you can see what actually moves the numbers.