Can I set Hide Sidebar as default in Preview Preview has become rather annoying. I found a post to Hide Sidebar https://apple.stackexchange.com/a/213395/19086

Even worse, if I select Full Screen mode I get Sidebar plus 2 pages side by side (which actually makes the document smaller and harder to read). Can I stop this?
In Full Screen you can hide the sidebar by unselecting View>Always Show Sidebar (shortcut optioncommand1): 



To get rid of the side by side view you need to select View>Single Page (shortcut commmand2) instead of View>Two Pages: