That didn`t work because i can only install on another flash drive... not the same one that i booted on
But i found a solution and it was exacly the one i wanted

Start knoppix with cheatcode "adriane">>>on the adriane menu select setup>>>go down the menu where it says "Persistent image on flash disk" or something like that>>>set up the number of megabytes for a persistent image>>>wait for the process to be done>>>reboot computer and start knoppix normally