Okay here’s how to do it. (using method 7)
Note: I assume you have 2 different OS’s in sda7 and sda10, namely Ubuntu and Kubuntu.
If they are the same distro, let us know.
If commands have been done, it’s okay to do again.
First boot into Manjaro and at terminal
sudo grub-install /dev/sda
Note; it is /dev/sda not /dev/sda9
repeat: it is /dev/sda not /dev/sda9
Then boot into Opensuse, at terminal
sudo grub2-install --force /dev/sda5
note: it is /dev/sda5 not /dev/sda
and for suse (and fedora, mageia…) it is grub2-install, not grub-install
Then boot into Linux Mint, at terminal
sudo grub-install --force /dev/sda6
note: it is /dev/sda6 not /dev/sda
Then boot into kubuntu, at terminal,
sudo grub-install --force /dev/sda10
note: it is /dev/sda10 not /dev/sda
Then boot into Ubuntu, at terminal
sudo grub-install --force /dev/sda7
note: it is /dev/sda7 not /dev/sda
If you install any new OS at installation make grub install to own partition and not to mbr
Remember to update-grub at Manjaro OS after that.
ps: you may want to consider the other methods (1) - (6)
I use method (6) and I don’t have to worry about any grub-update anywhere anytime or when I install new OS.
But since you’re having so much unnecessary problem here, I’d recommend you just uninstall intel-ucode (method 3) in Manjaro. Any OS grub will boot Manjaro okay then.