There's an old, archived discussion thread about the nuisance that Preview by default opens windows that are too small. It recommends using the Preview Preferences>PDF menu item to increase the default document scale.
But this doesn't work! For example, I tried setting it to 200% (the default was 100%), but after doing so, when I open a document it still opens at the same size. Furthermore, when I quit and reopen Preview, the settiung reverts back to 100%. I tried deleting com.apple.Preview.plist, but this didn't help.
Why is there an inoperative Preview preference? Is there a way to make it work?