@Switch Blayde
I access the site on my laptop. When I read a story on SOL (not bookappy) it uses the wide margins I define (so it looks like the page of a book). But when I sample a novel on bookappy, it fills the entire screen and is overpowering and hard to read.
I'm one of those obnoxious authors who likes to cram as many words on a page as possible, so while I maintain set margins, I don't make them as wide as you're describing, rely on indents rather than blank lines to designate new chapters, AND justify the text (which Lazeez has never been crazy about). In my defense, those publishing standards help speed reading of along tracks, but are largely useless for shorter (sub-novel length) stories.
The nice thing about the Bookapy approach is that it leaves the formatting up to the individual authors. While I don't object to readers changing their own formatting, since I put a LOT of graphic elements into my stories, his approach saves a LOT of trouble, as I'd need to butcher my books before posting them otherwise (as I've long done on SOL).
Unfortunately, you can do one or the other, taking the published book as is, or enforce your own standards, you can't do both.