I've been trying to get to grips with GRUB2 which has now become the default boot loader on Fedora. In the past if you had wanted to edit the boot menu it was a simple matter of vi'ing /boot/grub/grub.conf
The new grub configuration file (/boot/grub2/grub.cfg) explicitly states not to edit it manually.
The method now is to edit /etc/default/grub then run this command as root (or sudo):
grub2-mkconfig -o /boot/grub2/grub.cfg