What version of Premiere Elements are you using and on what computer operating system is it running?
Please review the YouTube Advanced Encoding document
Let us explore how that applies to your situation.
What is your project preset?
What are the properties of your source media?
Are you uploading your Premiere Elements Timeline from within the program's YouTube feature?
If so, what is the preset that you are selecting there prior to upload from there?
Please define your 1080...
1920 x 1080 16:9 @ ......
1440 x 1080 HD anamorphic 16:9 @.....where the 1440 x 1080 is stretched by the 16:9 flag to 1920 x 1080 for display after encoding.
Let us start here and then decide what next.