GRUB_DEFAULT=saved Apply the change to grub.cfg by running:
grub2-mkconfig -o /boot/grub2/grub.cfg Now list all possible menu entries
grep "submenu\|^\menuentry" /boot/grub2/grub.cfg | cut -d "'" -f2 Now set the desired default menu entry
grub2-set-default "<submenu title>><menu entry title>" Verify the default menu entry
grub2-editenv list 