export using quicktime imovie '11 9.0.9 on High Sierra

Hi, I have iMovie '11 9.0.9 on High Sierra. The problem I am having is that the last project I worked on in iMovie 9.0.9 was saved as a .mp4 prior to updating my laptop to High Sierra. I updated to High Sierra and now iMovie 9.0.9 is only saving my projects as .mp4 without an option to change the format when I try to export using Quicktime . My iMovie 9.0.9 has always done a poor job of exporting as a .mp4 in Quicktime, so even when I try to change the extension to .mov it has that pixelated look as if it was a .mp4. Not sure how to fix or get back to being able to choose the format when exporting using Quicktime. Any guidance or suggestions would be greatly appreciated.