I've been trying to create videos for YouTube for a while now, however, the main issue I seem to be having is with Windows Movie Maker. What happens is when I use Movie Maker to edit a video, it always lowers the quality of the video, and it adds black bars on the top, bottom, left, and right sides. I've checked the aspect ratio, and it's 16:9, with a 1280 by 720 resolution, so I know it isn't that. At the very least, if someone could help me either get rid of the black bars, or just point me in the correct place to find a solution, that would be amazing. Thank you!

This is what the videos look like before going through Movie Maker edits.

This is what the videos look like after the Movie Maker edits.