Go to Settings > iBooks, where you can:
Sync collections and bookmarks (including notes and current page information) with your
other devices.
Display online content within a book. Some books might access video or audio that’s
stored on the web.
Use the cellular network. Downloading books and audiobooks from the iBooks Store and
displaying online content within a book over the cellular network may incur carrier
charges.
Change the direction pages turn when you tap in the left margin.
Turn full justification on or off.
Turn auto-hyphenation on or off.
Set the number of seconds to skip within an audiobook when you swipe the book cover
or tap the skip button.