Article: Visit netflix.com/MoviesYouveSeen or click Ratings in your Account preferences. Click the stars to assign each movie or episode you've seen a rating from 1 to 5. The more you rate, the more accurate Netflix's recommendations will be.  You can also search for any movie and rate it from the description page. Do this for all your favorite movies to greatly increase recommendation accuracy. Click the "Not Interested" option underneath the rating if you never want Netflix to recommend that film to you. It may take 24 hours for Netflix to update its recommendations. Once this has happened, your recommendations should change on all devices you use to browse Netflix.

What is a summary?
Rate movies. Wait for changes to take effect.