i think what you want is here;
https://askubuntu.com/questions/1604...u-at-boot-time.
i also suggest you dl grub-customizer. with grub-customizer, you can make adjustments to your grub menu, font, colour, add a background pic and it will save your changes. you can choose to have the menu show up every time you boot up the system. i use it to make the menu not so boring and I do have the grub menu at every bootup. since it makes major changes, you have to use your pw every time you use the program. i am surprised that no body suggested doing what the askubuntu article says.