New-kernel-installed-but-does-not-show-in-grub (part two)

I have an identical problem to a previous topic but the topic has been closed. I have two instances of Manjaro on this PC and it appears I am booting with the GRUB of the other Manjaro installation. Implementing the indicated solution returns:

$ sudo grub-install --recheck --no-rs-codes
Installing for i386-pc platform.
grub-install: error: install device isn’t specified.

I am nervous about trying my own solutions as messing about with kernels broke the previous installation so I’d welcome some advice before proceeding further.

You will need to know what kind of system as grub installation differs for each type

  • EFI

The command which gave an error message is partly a command for BIOS/MBR. Blindly executing grub-install commands without knowing the system will most likely cause not only errors but possibly other problems as well

My partition table is: GPT .

You are correct, I blindly issued a command that ruined my previous install. Sadly, it is how I seem to learn!