And then...
...I got the ugly white border on my PDF.
I tried the old trick of unchecking the "Scale to Fit Paper" box, but it didn't work. It just cut out the edges of my cover page. Ugh! I had to step away from my computer for several days. I was too frustrated after trying to figure it out for nearly 3 hours. But a few days later, I was determined and I did it. I figured it out...in less than 10 minutes. In case there's someone out there in the world that encounters the same issue, I'm hoping this post can save you some time and frustration.
Step 1: File ➔ Page Setup ➔ (enter desired page dimensions) ➔ Options
Step 2: Paper Size ➔ Manage Custom Sizes
Step 3: Add (+) ➔ (type in desired custom size name)
Step 4: Paper Size (mine is 8.5 x 11) ➔ Set all margins to "0" ➔ OK ➔ OK
Step 5: Print ➔ Paper Size. Select your custom size you set up in Step 3, mine is called "Edge to Edge."
Step 6: PDF ➔ Save as PDF
Step 7: If you want to secure the PDF, check the "Require password to copy text, images, and other content" box and enter the same password twice. OK ➔ Save
I hope that helps!