Hello there, gruversm.
The option to set a preference for printer option isn't available. Its file size depends on the default size of the previously selected paper.
However, we can go to the Mac desktop settings and change the file size from there.
I've also added this article for more information on the recent update of QuickBooks Desktop for Mac: Release notes for QuickBooks Desktop for Mac 2020.
I'm just a post-away if you need help. Take care!