Question How do I install a UEFI Windows 10 instead of Legacy?

[ScreperisLT]

So I have just bought a new Ryzen 5 5600 along with a B550M Aorus Elite. I have updated the bios to the latest and have done nothing else. I installed Windows 10 with my Samsung USB Flash Drive and then tried going into BIOS and changing some settings. Out of curiosity I have turned on a setting called ,,CMS Mode" and now my Windows 10 in System Information shows BIOS Mode : Legacy, instead of UEFI. I also cannot turn off the CSM Mode, because every time I do, the system cannot find any bootable drives.
Of couse, maybe the Windows 10 already installed in BIOS Mode : Legacy, I just did not check it. I want to use GPT and not the MBR.
I am going to reinstall Windows 10. How do I make sure that this doesn't happen again? I am now going to use Rufus to make sure the Flash Drive is GPT and not MBR. What do I do from here? Do I just disable CMS Mode in BIOS and hope that my drives show up in the Windows 10 Installer? Should I convert the drives to GPT manually before install?

My drives : 1TB HDD, 240GB SX8200PNP M.2
My motherboard : Gigabyte B550M Aorus Elite

 

[TerryLaze]

You have to find a different setting in bios that will say something about restoring default security key for it to find the old installation.

For a new installation it should be enough to just disable CSM and enable secure boot. Emphasys on should.