Oh, sorry, it slipped me. You will find these options in a file called menu.lst, found in /boot/grub. You must edit it as root, I usually do it using sudo:
sudo pico /boot/grub/menu.lst
. Or, use 'su' to switch temporarily to root account, edit the file then type 'exit' then Enter to return to normal account.
Anyway, a backup of the file is welcome.