Two Manjaro Partitions but boot same Grub

I have two Manjaro Partitions each has its own boot profile and each profile is completely different looking when it comes to displaying grub. One is the slick green Manjaro background the other the old rectangular shaped grub listing the possible OS to choose. I have changed my bios UEFI to boot from one OS or the other, which ever I choose when using the bios to change the bootable partition. My problem is that no matter what OS I tell the bios UEFI to boot, the old grub boots for either OS. I have used update-grub in each partition but still no change. Any thoughts. Thank you.

Have you tried reinstalling grub-theme-manjaro ?

Not yet but sounds like a good idea. My question really pertains to which partition is UEFI booting from. Grub would show Manjaro1 as the first choice in grub if I booted from the EFI in bios and Manjaro2 as the first choice if I booted from a different EFI in the bios.

You should reinstall Grub from the distribution you want to have control over it

I’m not currently near a UEFI Manjaro system to quickly check in detail but if as normal you have the ESP mounted OOTB it should/can be enough to after booting into said distribution say

sudo grub-install

This would be detail enough on Ubuntu/Mint in any case. If it complains in the case of Manjaro you may need

sudo grub-install /dev/sda

or with /dev/nvme0n1 if that’s the drive you’re installing onto, or perhaps need to be even more specific as per e.g. point 3 of UEFI - Install Guide - Manjaro. Also run the subsequent

sudo update-grub

so as to generate and use the desired /boot/grub/grub.cfg from that distribution.

In any case then; new Manjaro user so pardon the uncertainty as to how to “properly” reinstall Grub from it but the point is: (re)install Grub from the distribution you want to have control over it.

Thank you for your in depth reply. I did exactly as you advised, grub-install on the partition I want to be the controlling partition. Works fine now. Thank you.