You have referred to that posting of yours, about UEFI, before. The answer then seems, If a computer uses UEFI, NO BOOT MENU is available. The user must change his settings, because the Windows 8 or 10 computer has no Boot Menu for making the boot device selection each time he starts the computer.
Imagine this morning, I want to start the computer and choose to boot to a bootable usb flash drive. Later in the morning, I want to startup the computer fresh, and choose to boot to a live CD or DVD. Maybe I find one day something is wrong with Windows and I cannot let computer boot into Windows, so I want the boot menu so I can boot into something other than the main root drive, like into some bootable CD, usb flash drive, or something other than "C" drive.
I guess then the only answer is, go into one of the F2 or F12 menus at startup, change some boot priority order settings, and then startup the computer again.
In case helpful, I have Dell Inspiron, Windows 10, and Dell support has not been too easy to understand and will not say specifically what to do. Meanwhile I will look at your posting one more time in case I actually actually learn something about this.
Edited by cafejose, 15 October 2016 - 12:12 AM.