How can I reinstall GRUB Bootloader on MBR after installing Kubuntu?

I installed Ubuntu, but then installed Kubuntu over it (formated Ubuntu Partition) because Ubuntu is not compatible with almost any hardware on my PC. Problem is I'm stuck with an old GRUB that says Ubuntu in the options because in my attempts to make it compatible with my hardware I got an old Grub with an image with an Earth that says Debian.

How can I replace the GRUB with the one Kubuntu is supposed to install. I don't want to modify just the text, or the command to install on /sdaX, I want to actually re-write the MBR with the latest grub (reinstall the bootloader).

Thanks.

If you are running Kubuntu, it's easy.

From a command line, assuming a single disk drive, type

sudo grub-install /dev/sda (this installs it in the mbr),

and then type sudo update-grub (this updates the grub menu)