Some find the mobile device transfer confusing. To load or delete a WMA or MP3 book onto an Apple mobile device do the following.
1. For Windows versions, you must first do a security update of Windows Media Player (even though you won't be using it) using Internet Explorer at http://drmlicense.one.microsoft.com/indivsite .
2. Open iTunes, plug the mobile device into the computer USB port and open the Overdrive Media Console.
3. Highlight the mobile device in the left hand menu of iTunes and insure the "Manually manage music and videos" box is checked in the Summary Tab.
4. Highlight the book you want to transfer in the Overdrive Media Console and click the Transfer Button. A window opens permitting you to click the boxes for parts of the book you wish to transfer.
5. After the book has been transfered, when you click the disclosure triangle (arrow) to the left of the iPod, iPhone, or iPad in the Device section of the left hand menu of iTunes, MP3 books will show up under the Music subsection and WMA books will show up in the Books subsection. Once the mobile device is disconnected from iTunes, MP3 books will show up in the Songs list and WMA books will show up in the Books list.
6. To remove a book from a mobile device plug the device into the USB port and open iTunes. Click the disclosure triangle to the left of your iPod, iPhone, or iPad in the Device section of the left hand menu of iTunes so that you can see the device’s subcontents. For an MP3 book select the Music subsection, right click on the book and choose Delete. For a WMA book, select the Book subsection, right click on the book and choose Delete.
The Windows version of Overdrive does convert WMA to MP3 format in order to move ebooks to Apple mobile devices. Unfortunately, the Mac version just won't deal with WMA. Though there are lots of audio conversion programs out there for WMA<>MP3 conversion, the security stuff on audiobooks prevents them from working.