Knoppix on USB, settings do not save

Hey guy I need help, I have Knoppix installed on a USB thumbdrive it works great. There is only one problem, the desktop settings do not save. I have looked on forums on how to do it. But there is an error when I try to go though the steps. One problem is when I go to Knoppix menu > Config > Save Config it keeps saying it can not save because the disk in use. Also I can not write files to the mounted USB drive. It gives me the same error, disk in use. Can someone help.