Windows Movie Maker saving parts I cut out

I made a video just how I want it in Windows movie maker (took a long time). But it’s perfect when played in there.I saved it as HD and in mp4. When I play the video back it includes parts I’ve edited out. I’ve gone back into WMM and the bits I don’t want are definitely gone, I even slowed the video right down to delete these parts again, and they are not there in WMM only in my saved copies.I can’t edit out what can’t be seen in WMMwhy is it doing this and how do I fix it?(It’s happened before but I just left it. But with this video I can’t it ruins the video)