I love reading on my Kindle Paperwhite. Sometimes, however, the screen exhibits ghosting—you see light gray text, lines or images instead of a plain background. The quickest way to fix that is to tap the top of the screen to open the quick settings menu. That action triggers a full screen refresh. The screen goes all black for a split second, which resets the entire e-ink screen. You can also force a full refresh on each page turn—which is how early Kindle modles always worked—with a setting that I think is hard to find. Look for the Page Refresh setting in Settings > Home and Library > Reading Options.