There's a slight disconnect between understanding a concept and being able to explain it to others so they get it.
What's clear in your head may still be hard to explain.
Telling the story reinforces your knowledge and improves your understanding, a process teachers continually go through.
If you want to learn something better, try explaining it out loud, with or without an audience.
Write about it. Give a lecture. Record yourself.
Writing, recording, lecturing, or talking aren't just methods to capture ideas but thinking mediums that shape what's on your mind.