Click on each book. Press the sound button to stop music. If you have to, Click "See Inside", go to a code page, and use Ctrl + A to select all, Ctrl + C to copy and Ctrl + V to paste. On the bottom right of each code page, there will be an extension. You put the extension at the end of the rename bar when you save those files. So they can work. However, DO NOT forget the ".", and DO NOT put "No extension" as an extension. (Only for Log-Book).
Credit to: @8BitKawaii Whoever made the music Microsoft, for Notepad program