Europe has volume restrictions. If you go back to Settings/System/Reset and choose All Regions you’ll get more volume.
Your track number tags need leading zeros: 01, 02, 03. Sansas read the first digit first, which is why you get it playing, 1, 10, 11.
There is free software (in German, too!) called mp3tag that will do it easily.
or in English : http://www.mp3tag.de/en
Download the file mp3tagsetup (whatever version), not the other download buttons on the page.
When you install it allow itself to be added to context menus.
Under Tools set its Write to ID3v2.3 ISO-8859-1. The ISO is how Windows displays the alphabet, as opposed to UTF on Apples.
Right-click on your audiobook folder that’s not playing in order and choose mp3tag to open it. Click on the Track number header to display the tracks in order, top to bottom (make sure they are not flipped!)
CTRL-A to highlight all of the files.
Tools/Auto-Numbering Wizard/Leading Zeroes.
