Can't edit saved files on USB thumb drive

Have a TextEdit file on a USB thumb drive, if I open it, make changes, then try to save, it won't let me, says I don't have permission.

It allows me to duplicate it, make changes, then save the new version to the USB drive.

I have right clicked --> Get info --> checked permissions on both the USB drive and on the TextEdit file and I have read and write permissions on both, and I created both of these anyways, so there is no reason I should not have permissions.

Any idea what's going on here?