sudo apt-get install python-software-properties (install only if add-apt-repository doesn't work)
sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer
gksudo grub-customizer
sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer
gksudo grub-customizer