Is there more than one drive that has, or has EVER had, an OS installed on it? If so, there may be more than one boot partition still hanging around and you may need to eliminate the older system boot partition from whichever drive had the OS installed previously.
If not, then I'd suspect you might need to replace the CMOS battery since the settings are apparently not being saved. It could also just be a faulty motherboard BIOS ROM, which may be replaceable but usually means a new motherboard is in your future.
It may be worth your effort to simply remove the cmos battery, with the power disconnected from the power supply, for about five minutes, then put it back, boot into the bios, reset your boot priority and reboot.
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