Try F1 instead of F12. It should be under Setup -> Boot, and then just make your USB the first entry, save, and exit. And just so we’re covering all bases, the usb should be plugged in before you reboot into the bios settings and it may be under a name that doesn’t say “usb” anywhere (for example, the name of my usb in the bios settings contains the manufacturer and size in GB in addition to some other nonsense that i think is a model number).