Change project settings after footage is all cut up on Premiere Elements
you should be able to adjust everything just from the project panel.
See this, I dropped mp3 into 'new timeline' button and got this sequence -

All you need to do is go to sequence and select desired output

You can set everything here

For me, making the MP3 file into 'New sequence' defaulted in 1920x1080 29.97 sequence, but if you have issue that it made different format and you want to skip changing scale of every individual file (I'm assuming you might have got different format, like 1280x720, although unlikely), you can just setup an adjustment file above your edit, select 'distort - &gt; transform' from effects and adjust scale to fit to your desired resolution.