I want to install Ubuntu on my laptop. I entered BIOS(image below) 
Why I can not change boot OPTIONS? My laptop is HP EliteBook 8560.
System Summary shows
52 Answers
Partition mismatch could be one of the reason for usb not detected. You should try changing from legacy to uefi and check if the problem exist? In case you cant change the boot option, that may be because your secure boot is enabled. You first have to disable secure boot,you can enable that later after you change from legacy to uefi. This link down might help you guide to fix your issue:
@MikiBelavista have you tried disabling secure boot ? see the steps here (title says about CD/ DVD but it applies to USB too)