I see it all the time. I do it, too. I write merrily away, confident about my subject. The words flow, and I know I am on. Click Save; close the document.
A few days later I open the document, only to realize that not everything I wrote still makes sense. Pronouns don’t refer to any particular noun. Language is vague. Paragraphs aren’t orderly.
What is a writer to do with such lack of clarity? Plain and simple: remember to write in drafts. Get everything down as quickly as possible, then put it away for an hour, a day, whatever you have time for. Fresh eyes will give you perspective and help you to revise for clarity and meaning.
Try it.