Setup -> U Disk Mode -> Single
You may have to wipe partition table with fdisk and recreate one FAT32 partition.
Do not keep formatting unless absolutely necessary, that cause unnecessary wear on flash chip.
To be sure it is really 8GB, open the player and check the part# of the flash.
http://www.samsung.com/global/busine...Nand_Flash.pdf
http://www.hynix.com/inc/pdfDownload...ND%20Flash.pdf
8GB = 64Gb