You can find out the UUID using the blkid command
Use the UUID showed here corresponding to your USB device. Exchange that together with the example from fiewtoid
Does that help?
sudo blkidThis results in a list like this
/dev/sda1: UUID="1123a4b5-9a23-4645-9101-7a43059cfe8a" TYPE="ext4" PARTUUID="6fedd353-01"
Use the UUID showed here corresponding to your USB device. Exchange that together with the example from fiewtoid
"UUID=1123a4b5-9a23-4645-9101-7a43059cfe8a /mnt/usbdrive ext4 defaults,errors=remount-ro 0 1"
Does that help?