Full F2 and F12 settings to enable boot from Recovery USB

On every Dell non-server system I've used, pressing F12 during initial boot will cause the one-time boot menu to appear, and as long as your USB device was properly set up as a boot device and was already connected when the system powered on, you should see an option to boot from it in that list.  If you mucked around with BIOS settings, you might want to consider going into your BIOS Setup by pressing F2 during initial boot and choosing to reset all BIOS settings to their defaults before trying the F12 boot menu method, because there are definitely some changes you can make in the BIOS that would interfere with USB booting.

Another option would be to just use Windows 10 installation media created by the Microsoft Media Creation Tool.  Assuming you're trying to install Windows 10, that would be here.  It might contain a newer Windows 10 release than the Dell recovery media anyway.  It might not include some of the drivers that the Dell media would, but you can use Dell Update or Dell SupportAssist to get those back fairly quickly.  I've personally never used the Dell recovery media, so I don't know exactly how it sets up its USB media.

So, here are the current settings in the BIOS. I have the USB Recovery Tool (though of course I may take up the suggestion of creating the Recovery Tool direct from Microsoft) and just need to know the optimal settings for me to be able to boot fromthe USB... because currently it does not work.
Just to note - I have previously set the boot options from USB once the USB has been inserted.... it just goes to 'Preparing Advanced Repair' loop again... and again... and again..... 

F2 MAINF2 BOOTF2 BOOT - UEFI dropdownF2 ADVANCEDF2 SECURITYF12 BOOT MANAGER

Your BIOS settings look good except that you can and should enable Secure Boot if you’re using Windows, since that’s been supported since Windows 8 and is a nice anti-rootkit security measure. But having that disabled certainly that wouldn’t explain your USB device missing from the F12 boot options list. If you haven’t already, try using a different model flash drive. I’ve seen cases where certain systems simply won’t boot from certain flash drives for some reason. Another thing to try would be creating generic Windows 10 installation media using the Microsoft Media Creation Tool. If that allows your flash drive to be detected in the boot menu, then it sounds like something isn’t being set up correctly by the Dell Recovery Media creator.

@U2CAMEB4ME .... (Yes! I managed to tag you!)
This is the new thread after the one you helped me with in creating the recovery tool... Thank you for your help - if you have any advice on this next step I'm all ears! 

Thank you JP - I will enable secure boot. 
Will also try a few more times with my current USB. There are 3 USB ports and I have noticed that it is recognised in some and not others... but even when it is selected for boot it doesn't boot. 

So - will keep trying and will also try a differed USB stick... and the Microsoft recovery media.... I am determined to breathe life back into this machine! Its too young to die!

I forgot my password and I cannot get into my computer with this setting