I found the menuentry/subentry that I wanted to use, as you can see here: https://gyazo.com/b73fa2308145caaed7959a95d71a4bc8
I then changed this in /etc/default/grub to this: GRUB_DEFAULT=1>0
I updated grub with: sudo update-grub
And then rebooted the system with: sudo reboot
It still loads into the same old kernal.
I am using Ubuntu 16.04.