I recently installed windows 7 using a usb drive i followed all the steps i found online and it worked fine I'm running the windows i put on it right now. I did this all on a usb 2.0 and i just got a usb 3.0 so wanted to put it on my newer/faster usb 3.0 drive. So i did everything i did the first time and when i went to go test it i found the boot off usb option in the bios clicked it and restarted but it just went straight to windows so i went back into the bios again and the boot from usb option is now gone i restarted my computer multiple times and even tried my old 2.0 usb drive which i first used to install windows 7. I tried both usb's with every usb slot i have and they both work fine in windows and both show the windows boots icon. I have a GIGABYTE GA-Z77X-UD5H motherboard with the latest bios.
Make sure that in the BIOS setup, USB Legacy support is enabled.
On this motherboard the boot settings reset after boot. to boot from USB check the BIOS Features Tab and check the boot priorities. to boot from USB, UEFI should be first. Install the BIOS utility that came with the motherboard. it appears this BIOS is meant to be configured with that.