Premiere Elements is a best selling video editor around the world. This is one of the least active forums on the internet. Only a few of the thousands, maybe millions, of Premiere Elements users show up here. The logical conclusion is that there is little wrong with it and there may be something wrong with your computer, the installation or your choice of video files.
Before version 15, Quicktime was required to be installed so that Premiere Elements could use some of it's parts. Adobe no longer lists it as a requirement for version 15. But, there have been situations where some video file types won't work. The solution is to install Quicktime.
Apple stopped supporting Quicktime for Windows and some suggest it is not safe to install it. In the installation procedure there is an option to install only the support files and not the .exe itself. The other is to rename Quicktime.exe to Quicktime.bad so it won't run, but the support files remain.
Some dislike Adobe and are angered by all they do. Cyberlink and Corel have low priced alternatives. Magix has a couple of choices including what was the Sony Vegas and Movie Studio. Video editing is complex enough that all have those that love their choice and a few that are angered to the point of quitting. I'm one. I couldn't make Sony Movie Studio run on my computer for a month. So I changed to Premiere Elements and updated every other version since 9 without any difficulties.
Good luck with your projects!
Bill