In both the iPhone and Android versions of The A.T. Guide PDF Reader App, the highlighter can have trouble highlighting several lines of text. This is a limitation we have to live with to be able to offer annotations, a mileage log, and a highlighter. We prioritized the functionality of the other higher value features while still being able to offer all three functions. The work around is to keep your highlights simple. If you can not highlight as much as you want in one highlight, use a few smaller highlights.