In the movie Amadeus, there's a scene which he improves Salieri's work in front of the Prince. Whats the name?

Answer 1

When Mozart meets the Emperor for the first time, Salieri presents Mozart with a little "March of Welcome". Mozart "improves" this piece later in the scene, transforming Salieri's "trifle" into the "Non più andrai" march from his opera, The Marriage of Figaro