Q: How do you reformat a USB drive into a single FAT partition?

I'm having the worst of worst times with Windows 10 Boot Camp. I managed to get it fully installed once and all my drivers installed, but when I restarted it, I was no longer able to make it past the login screen because the screen would go black and only the cursor was seen (I'd determined that it was a driver issue as many people seemed to have this issued). After talking with both Apple and Microsoft support (neither which could conclude my problems), I decided to just uninstall the partition and reinstall.

That's where I ran into trouble.

Although there was nothing on the USB flash drive I was using when i tried to put the installer file on it kept telling me that there wasn't any space so I went into Disk Utility and erased, which also coincidently formatted it. Apparently this was a bad idea because now Boot Camp keeps giving me this error: "Please format the USB drive as a single FAT partition." I go back to Disc Utility and let it reformat as a MS-DOS (FAT) but when I do this, it tells me there isn't enough space on my flash drive to do this. The only one that will let me put my file on it is when I format it as the OS X Extended (Journaled) but then it won't let me go through Boot Camp without the above error coming up.

I've done Boot Camp before on somebody else's Mac and it was so difficult, and now I'm trying to do it for myself.

I would just like some help.

Big thanks in advance!