In BIOS settings, System tab at top side.
By the way last BIOS for your board is F53 from January 5, this year. Seems is worth to try.
https://www.gigabyte.com/Motherboard/GA-A320M-S2H-rev-1x/support#support-dl-bios
Well, try switch from UEFI to CSM boot mode and then boot into that Windows you already have on M.2 drive. If id doesn't help, it seems you will need to switch back to UEFI and reinstall Windows on M.2 drive with other drives disconnected at that time.
Also seems that for your motherboard BIOS update can be done only from Windows. And you didn't said which GA-A320M-S2H board revision you have (there are three of them, it matter).
He have different hardware with different driver set and different system configuration - what do you want?