If you've set the region as European at the initial set-up, the available volume level is limited to 7.

1) Delete the SYSTEM folder by right-clicking "delete" on the menu after connecting the device to the PC and reboot it.
2) Turn on the device by pressing and holding the play/pause button.
3) Set the display language after selecting the language icon in Setting using FF/REW and play/pause buttons.
4) Select No European after selecting the region icon in Setting
5) Set your FM Region after selecting the FM Region icon in Setting