Black Borders with Movie Maker, CANNOT FIX!?

I have a 1680x1050 monitor and I record my gameplay using NVIDIA ShadowPlay in 1920x1080, when I open it in Movie Maker there are black borders and I make it 16:9, save it in 1920x1080, upload using yt:stretch=16:9, crop, etc. NOTHING WORKS, I know it's not the aspect ratio that's my issue, because if I upload a video without putting it in Movie Maker, all I have to do is type yt:stretch=16:9 and upon uploading to YouTube the video can be restored to 16:9. But the problem is I need to edit the videos so I have to use Movie Maker, and I don't want to switch to a different program for 3 reasons, one I am new and I want to start basic, two I know Movie Maker really well, and three I don't have money for like Sony Vegas or anything, (yes I know there are other free programs out there, but I still have those other two reasons to worry about.)

Anyways, please help I have been looking for a couple days now to find a solution to this and I cannot!