Setting default boot kernel in Grub on Debian/Ubuntu Rumi, June 6, 2014 In a terminal, run sudo update-grub Then, type grep menuentry /boot/grub2/grub.cfg Counting from 0, find the number of the line containing the 2.6 entry you want. Set that as default in /etc/default/grub and run sudo update-grub again. Since the option for "Other Linux Versions" is on line 3 of the Grub menu, I changed the line in the /etc/default/grub file from default 0 to default 2 Configurations (Linux) Grub