I've just bought a new laptop for Deidre and have been going bog-eyed setting it up for her since noon today. All is done - except.....I want to change the boot sequence to allow booting from an external source. This makes it easier to recover the machine, if necessary, by booting from a CD or USB with Acronis on it.
It's a cheapish ACER Aspire 3, 15.5" screen, Intel core i3 and a 128 GB SSD, running the ubiquitous Windows 10 Home.
I've always set the boot source as firstly, an external drive - usually an optical drive, (lacking in this Acer) and secondly, the main Windows boot area of the internal HDD.
There is no alternative boot source shown in the BIOS, just the internal SSD.
Not sure I can help but how are you reaching the boot options screen?
One of the "new" Windows 10 recommended ways is to right click the Windows logo, click Settings then Update and Security then Recovery then Restart Now under Advanced startup. You then see some options including choosing where you want to boot from.
I expect you'll only see the same as you are already seeing though, and I've not yet considered why this is an improvement on the old method of tapping a function key at startup to get the BIOS screen up.
Conceivably your menu may only offer options which are actually available i.e. if you put in a bootable USB device that might cause it to appear in the menu. Many years ago that's how our mini-computers worked.
I opened the BIOS setup in the usual way (F2 when restarting) and got the usual display which I was expecting.
navigating along by the arrow keys, as usual, to boot options and only saw what I mentioned above.
One of the other options I saw was "safe boot enabled" , which was apparently changeable, but I left it as it was. Maybe disabling that would show other options?
I may well try creating a bootable USB drive, as you suggested, to see if that alter boot options.
The trouble now is prising the machine out of its new owner's hands!
I think there is an option concerning USB support at boot. Perhaps under advanced settings. Something like none, partial and full. Originally it was there to speed up booting by not dicking around with USB devices.
If that support is not enabled, then perhaps it can't use it to boot?