changing margins or scaling pdf on ipad

If you look at the attached images you'll see that the text margin is right on the left but is pushed almost to the edge on the right. And there's that big gray box.  I've searched extensively and found no way to scale pages on the ipad app. I find it very difficult to work on a manuscript that is so lopsided.

I should add that this document is more than a thousand pages long, so the liquid page feature isn't available.

Any suggestions much appreciated.