How does BIOS turn on UEFI mode?

Boot into the motherboard BIOS first, and the OS option has been set to be disabled when restarting;

However, the UEFI option under startup is gray and cannot be changed;

At this point, you can restore the BIOS default settings;

Can be changed after recovery;

If it is still gray and you can't choose, or you don't want to restore the default, you can enter the security option and find security.

Boot (safe start);

Close the safe start;

You can change UEFI, as shown in the following figure:

(I hope the landlord will adopt it)