I had a similar experience while trying to export videos in MP4 format. What worked for me was using a different video editing software. I switched to Video Editing Software with NO Watermark, which I found at https://www.movavi.com/learning-portal/free-video-editing-software-no-watermark.html It's user-friendly and has many great features for both beginners and advanced users. It allows you to trim, cut, join, and enhance clips with various effects, including titles, filters, transitions, and chroma keys.