It doesn't make any sense. He contradicts himself. If you bought a computer in the store (not tech savvy) then you are fine. If you built your own computer (tech savvy) then you can't figure out the bios settings?
MBR/GPT and BIOS/UEFI aren't anywhere in-depth as clock multiplier, bus master/slave or IRQ/DMA/IO.
MBR/GPT and BIOS/UEFI along with SecureBoot are neatly explained in the UEFI and motherboard manuals. Also custom parts imply you're running XMP memory and need to enter UEFI to enable the advertised clocks anyway (Hello! JEDEC).
UEFI and GPT have been on the scene since Vista (2007).