How to boot from usb?

Question

I have a bootable usb device. I attach it to pc, and open bios settings. My settings are :

• Advanced

  • USB Configuration
    • legacy usb support - enabled
    • xhcı pre-boot mode - enabled

• Boot - Boot Configuration

  • Fast Boot - enabled
  • Launch CSM - disabled (not editable)

• Boot - Boot Options Priority

  • Windows Boot MAnager

  • Ubuntu

  • Ubuntu
• Security - Secure Boot Control - Disabled

There is a efi folder in my usb device.

I can't start pc on usb device. I want to install a new ubuntu version on old version using a usb bootable device. How can I do it?

EDIT

I use a diffrent usb device. I can start pc on usb and install ubuntu.

Answer 1

After burning ISO of Ubuntu to flash drive you have to start your PC enter BIOS SETTINGS then change boot sequence put usb or flash drive whatever it is written at top and save chahges. What happens is that now you have configured BIOS to check usb is attached any for some OS. If it fails it moves to check on second and third storage device ex - HDD. If Ubuntu is burnt correctly ubuntu will boot but it will slower much slower then being installed in HDD.

Answer 2

You should probably have Fastboot disabled.

Also, the boot sequence should be such that you give a higher priority to the USB drive that you have plugged in, as compared to the HDD that is inside the machine. Currently, I can see that you have put the Windows Boot manager at the top priority.