Video made and saved, does not play when I try to view it.

I made a video (about 8 clips with music). This is my first video with Premiere Elements 2023.

I get a couple of "errors".

First is the pop up telling me that the file(s) I selected for my video work place do not match my project settings.

I do not know what that means or how to fix it.

Second is that after making all the clip/cuts, adding music, saving and exporting the video, it starts to play for about 2-3 seconds and then it stops and tells me it cannot play.

I have used Photoshop Elements & Premiere for years but this version seems to be causing me considerably more problems than previous version. I do admit I am not a pro, just an amateur so the technical aspects are confusing to me.

If more details are needed I will try to provide them.