How do you change the default aspect ratio for movies?

I have a movie with a default aspect ratio of 4:3, but really the movie is better in 16:9. I can change it temporarily with VLC, but when i go to burn it onto a DVD, it will be in 4:3. How can it change the movie's default setting?How do you change the default aspect ratio for movies?im not sure if u r using a dvd converter or not but i know if u use those they let u pick the size ... i use ConvertX to DVD full version it lets me do it ... if u need help finding it pm me