by "changing one letter", Im assuming you can change "the non-existant letter place holder" to a letter. In short, make words other than 4 letters.
You shouldn't judge a book by it's cover, instead, you should read every single book to see what every book is about before you even come close to judging its viability.
A person is more than their experiences, stacked up like stones... Our best moments are the foundations we use to reach for the sky. — Yumi and the Nightmare Painter by Brandon Sanderson