Edit Scale

When I initiate a new document and have it set to Page Size to Letter, the page dimensions change as I edit the scale under tools. The home page layout of 8½ x 11" enlarges to 17 x 22" when I change the scale from 1:1 to 1:2. (It escalates proportionally as I change the ratio.)

This wasn't always the case - what do I need to adjust to keep the page size the same yet draw in the 1:2 ratio?