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>"
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>"