To enable you to play all tracks, just follow these three steps.
- Create a folder called 'Music' at the top level (root) of your USB hard drive.
- Move all music on your drive into this new folder.
- Now when the USB drive is connected to your player, you will have the option to play all the tracks by navigating to Music Library > 'USB Drive' > and pressing play on the Music folder.
If you don't have this 'Music' folder and instead have your artists as the top level (root) folders, then you'll only be able to press play on individual ones and add them to the queue individually.