The dreaded read-only problem

[Tyrannocaster]

I copied all the settings in that instruction page, changed the Disks options to match them, and rebooted. As before, the drive let me copy one file to it and then said NO to anything else I try. If I click on the desktop icon and check properties there, it now says the owner is root and every one of the option pulldowns is grayed out. If I open it as root in a file manager, I still can't do anything to it.