Below of some useful tips for Grub2, the open source bootloader. You are to edit the file /etc/default/grub. After you are done with any of the changes below, run
sudo grub-update
to apply the change.

1. Get rid of the submenu:

GRUB_DISABLE_SUBMENU=y

2. Set the default entry: https://help.ubuntu.com/community/Grub2/Submenus

3. If you want your Linux system to book into text mode/console/command line, just follow this http://ubuntuhandbook.org/index.php/2014/01/boot-into-text-console-ubuntu-linux-14-04/ Basically, you need to make the following changes.

3.1 Uncomment or enable the line GRUB_TERMINAL=console
3.2 Commend or disable the line GRUB_CMD_LINE_LINUX_DEFAULT="quiet splash" or whatever value on the right hand side of the equal sign.
3.3 Change  GRUB_CMDLINE_LINUX=”” to GRUB_CMDLINE_LINUX=”text”

4. Leave you a timeout for changing Grub at system boot

Remember to always set a non-zero value for GRUB_TIMEOUT, e.g.,
GRUB_TIMEOUT=10
in case something goes wrong.

But it is not terribly bad if you mess up. Just mount the drive in which you Ubuntu is installed, go to /boot/grub/grub.cfg to edit the settings.