You will want to post to the PrElements Forum.
Perhaps the MOD's here can move this for you.
There are two ways to upload to YouTube from PrE: a direct upload, and also an Export/Share, then manually upload.
Folk on that forum can help you determine which works best for you, and tell you how to do it either way.
Start by going to YouTube and finding their "specifications" page to learn just EXACTLY what they want from you
Also, as far as I know, ALL uploads are encoded by YouTube to fit their player screen... which I think is 320x240
The only time I uploded to YouTube was from a FlipHD camera... and the video looked fine after YT encoded to fit their screen