Q: I bought three John Grisham books and the info was in English but when I opened the books, they were in German. How do I convert to English.

You can't convert them. What language do the books description pages in the store say that they are in ? If English then try deleting them from the bookshelf in the iBooks app and redownloading them via the Purchased tab in the app - if they redownload in the wrong language contact iTunes Support : http://reportaproblem.apple.com

If their description pages say that they are in German then you could try the above 'report a problem' page to contact iTunes Support and see if they will refund or credit you (but purchases are considered final) : http://reportaproblem.apple.com

Or you can try contacting iTunes Support via this page : http://www.apple.com/support/itunes/contact/ or https://www.apple.com/emea/support/itunes/contact.html