"it's designed to run without passwords" - right, but the problem is more complicated than that, for instance, if you use the menu system to start the "Users and Groups" applet, it won't let you change anything. So I edited the menu entry to put "sudo" in front of the command line for the applet and it works fine. But these menu changes don't persist, so I guess I need to use that persistence file? Since it's installed on an 8GB SD drive, and it claims there is 4 Gig left, how big should I make the persistence file? I guess since Knoppix uses FAT32 - the biggest I can make it is ~2GB...