The instructions are clearly described at the bottom of the menu. All of the instructions described at the bottom of the menu (except for the E to edit pre-boot commands and C for command line) apply to this. Fullscreen is recommended for this. V1.0: Initial release V1.1: Added "Advanced options for Ubuntu" to the list of entries shown on the menu V1.1.1: Fixed bug causing none of the entries to be selected (rather than the last entry) when the up arrow key is pressed while Ubuntu is the selected entry V1.2: Added another new entry; this time, it is "UEFI Firmware Settings"
Credit to the Free Software Foundation (FSF) for the GRUB boot loader, and @SMB_Fan2010 (me) for the code and art for this project.
