I have recently purchased above PC second-hand and installed a new hard disk with Ubuntu 17.10 as the OS in place of Windows 10. Boot priority is to a Realtek PXE which I assume is no longer in place. I wish to add an SSD drive but am concerned I might be unable to alter the boot priority. I can access the BIOS (or is it UEFI?); it displays the new hard disk correctly as the second boot option and the DVD drive as the third boot option; but am unable to amend any of the BIOS settings except the password which I can alter.
Is anyone able to explain what is going on and how I might activate the various BIOS options?