there is secret command to change c-number. ZDCN !!!! There is no description of this command in NED, moreover, there is no such command in command menu ZDC? . But if you type ZDCN you’ll see command and it’s description!!!
be carefull, if you change c-number then all login/password will be lost, c-number used somewhere in password storyng alghoritm… even SYSTEM/SYSTEM will not work!!!