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
- Once 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 Name] > and pressing play on the Music folder
If you don't use a 'Music' folder and instead have your artists as the top level (root) folders, then you'll only be able to press play on individual tracks and add them to the queue individually.