How to change the GRUB2 menu for the RHEL7 installation via USB boot on the server with UEFI enabled

Issue

• I'm trying to customize the installation DVD to change the GRUB2 menu and the boot parameter.
• UEFI is enabled on the server, and USB flash media is used for booting.
• The installation media was customized by following [1].
• USB boot media was created with the customized installation ISO image upon [2].
• I modified /EFI/BOOT/grub.cfg for the purpose, but the installer didn't show the modified GRUB2 menu.

[1] https://access.redhat.com/solutions/60959

[2] https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/installation_guide/sect-making-usb-media#sect-making-usb-media-linux