I once heard of an experiment where people were asked to a song and get someone else to identify the song. Over and over, the people clapping would grow frustrated that the other person couldn't figure out the music that was completely obvious to them.
The clappers failed to comprehend how challenging the game was when you didn't have that song in your head. It's vital information that gives context and helps you understand.
Often people write the same way.
For them, the story and details make complete sense. It's apparent—if you have the song in your head. But your readers don't—unless you give it to them.
This effort takes practice and care. It requires getting outside perspectives to identify the things you can't. Once you get this information, work with these early readers to help clarify the details in your writing.
Help us hear your song.