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?
UEFI and GPT have been on the scene since Vista (2007).
No jumpers to set for CPU multipliers, IDE master/slave or IRQ/DMA/IO etc.
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).