How do I set the page size for PDFs in DC?

I've hit another wall with DC . Where the heck is Page Setup hidden, i.e., the place where to specify paper size?  I have a PDF that for some unknown reason suddely looks like some odd tall, skinny almost european format instead of 8 1/2 x 11" letter size like it did when I created the PDF.  And now I can't figure out where to change that. AD's help guide was no help again (told me to click something it called the the Windows "hamburger" menu, which I've never heard called that b4) and I can't even find that icon (it's so difficult to use icons in DC, it's a treasure hunt every time). I also tried Print/Page setup, but that didn't work (DC didn't show a list of paper sizes that I could chose from). 

This madness happens everytime I use DC. I used to be great with Pro, but DC is just horrible.  Can some kind soul do me a favor and give me a simple, menu-based way (no frigging icons I have to hunt for please) to set paper size?  

Thanks!