Does anyone know how to change this so my movie files open in 16x9?
A specific solution would depend on you specific problem. Since you have not told us much here, I can only guess at your problem. This situation is most commonly caused by editing/modifying/copying a PAR encoded file using a work flow that loses the PAR flag/value. In these cases older applications like QT 7 normally contains four separate pieces of "size" info -- the dimensions at which the content was originally encoded, the proper aspect ratio playback dimensions (usually in parenths), the "normal" playback dimensions, and the "current" playback dimensions. QT 7 always plays back the content using the "Current" dimensions which you say remain correct. So I assume your is an anamorphic file which has lost its flag and is being played back in a ewer application like iMovie '08/'09 or QT X. These applications ignore the "Current" dimensions embedded in the file and rely on the anamorphic setting for playback. Lacking the proper flag/value, these applications automatically fall back on the 4:3 aspect ratio default for playback. Basically, you have three options: 1) use a different work flow which retains your original file's PAR setting, 2) re-encode the file that has lost its PAR setting so you can use the new file in whatever application is causing the current problem, or 3) use an older application like QT 7 or iMovie HD which rely on specified playback dimensions that can be user modified if need be.
