[gentoo-user] Cannot edit files on usb flash drive.

[ubiquitous1980]

I have a usb flash drive which will not allow me to edit its files.  I
have tried chmod a+rwx -R $files but this does still not permit
editing.  Further, the files within the directories refuse to have
ownership changed via chown $myusername -R /mnt/disk.  Output is:
operation not permitted.  Any ideas?  Thanks.