Dual boot GRUB issues

[su:bhatta]

Hello after a long time .... Ah ! memories of learning to fix mistakes... good old days...
I have been stuck running a elementary for a long time.. blah...

Long story short... I am installing 2 OS on my laptop, OpenSuse Tumbleweed and Ubuntu 20.04. No Windows !!
I have installed them both and Ubuntu wrote its grub first and in which part of Disk i don't know !!
Opensuse wrote second and put the grub file in its own partition.I have to change boot option from BIOS to get default Opensuse to change

MOK screen comes up, errors show up that point (Google search, these forums) towards UEFI boot related issues...

I want to re-install the Opensuse due to issues (not only GRUB, Suse has own issues, installation?)

My question is, to get things corrected , in which part of Disk do I get Suse to write the grub?

Cheers all... any help is much appreciated.

If this is required :

Disk /dev/sda: 931.53 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: TOSHIBA MQ04ABF1
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 2711528D-670B-4E2D-A1B6-4F7A965FDEB8

Device          Start        End    Sectors   Size Type
/dev/sda1        2048    1050623    1048576   512M EFI System
/dev/sda2     1050624  136218623  135168000  64.5G Linux filesystem
/dev/sda3  1949329408 1953525134    4195727     2G Linux swap
/dev/sda4   136218624  271386592  135167969  64.5G Linux filesystem
/dev/sda5   271386624 1949329407 1677942784 800.1G Microsoft basic data

Partition table entries are not in disk order.

[CelticWarrior]

In all UEFI systems the bootloaders reside in the ESP (EFI System Partition), your sda1.

[oldfred]

Both BIOS & UEFI, you normally select a drive like sda on where to install grub.
With UEFI, it finds & knows to actually put the grub/ubuntu boot files into the ESP - efi system partition, your sda1.

Does your UEFI boot menu show both Ubuntu and OpenSuse as boot options.
You can also see those from system with:
sudo efibootmgr -v

UEFI remembers old entries, so if name/label in UEFI changes or you have old installs that you removed there may be old entries in UEFI and old folders in ESP.

[su:bhatta]

Thanks CelticWarrior!

Both BIOS & UEFI, you normally select a drive like sda on where to install grub.
With UEFI, it finds & knows to actually put the grub/ubuntu boot files into the ESP - efi system partition, your sda1.

Does your UEFI boot menu show both Ubuntu and OpenSuse as boot options..

Yes oldfred, in UEFI Boot both Ubuntu and Suse can be chosen!