Instructions on how to boot from a USB Flash Drive are given below listing.

Kubuntu on a Bootable Kingston 64GB USB 3.0 Flash Drive.

22.04.3 Long Term Support, Released: 08/2023, Supported until 04/2027

24.04 Long Term Support, Released: 04/2024, Supported until 04/2029

Install distro on PC or Laptop
Run as a live system - no need to install 
Optional Persistence can be used to store documents and settings.

USB Drive can be reformatted when system is no longer required.

This is free open source software. The charge I make is to cover my time, blank media, post and packing.

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When booting from USB media, you must change the BIOS boot order so the USB device is listed first. Otherwise the computer will load from the hard drive as normal.

Start by plugging the thumb drive into a USB port. Then to change the BIOS boot sequence:
    • Press the Power button for your computer.
    • During the initial startup screen, press ESC, F1, F2, F8 or F10. (Depending on the company that created your version of BIOS, a menu may appear.)
    • When you choose to enter BIOS Setup, the setup utility page will appear.
    • Using the arrow keys on your keyboard, select the BOOT tab. All of the available system devices will be displayed in order of their boot priority. You can reorder the devices here.
    • Move USB to be first in the boot sequence.
    • Save the change and then exit the BIOS Setup.
    • The computer will restart using the new settings, booting from your USB drive.
    • The installer boot menu will load.

UEFI/EFI configuration, Windows 8 and Windows 10 computers usually have the new UEFI/EFI that needs some configuration before you can proceed to boot from a USB flash drive.
Access to this is as above for BIOS
You need to disable the secure boot option. Alternatives names can be any of the following, depending on your computer model:
    • Legacy Support. If you have Legacy Support listed, make sure it’s On or Enabled.
    • Legal CSM. If you have Legacy CSM listed, make sure it’s On or Enabled.
    • Launch CSM. If you have Launch CSM listed, make sure it’s On or Enabled.
    • CSM. If you have CSM, make sure it’s On or Enabled.
    • UEFI/Legacy Boot. If you have a UEFI/Legacy Boot option, make sure it’s selected as Both or Legacy Only.