Restart computer press F2 to enter Setup (Bios) go to the Security tab. Look for Secure Boot, and Disable it. Go to the Boot tab. Here you will see the UEFI Bios. Windows Manager you can select Legacy/CSM Bios under Boot tab in the Bios. Save and Exit, then your current USB Flash Drive will be listed as a bootable device under the F12 boot menu.
Or You can take your USB Flash drive and recreate it using Rufus, under
Partition scheme: GPT
Target system: UEFI (non CSM)
https://www.aioboot.com/en/how-to-use-rufus-to-install-windows-10
Once created as GPT/UEFI it will be a bootable choice under the F12 menu