How do I switch the boot loader

[netipot]

I read on the forums about a month ago how to switch the boot loader from OS to the other in a dual boot. It was a simple command in terminal. I can find it now. I have ubuntu 12.04 & I recently installed lubuntu 12.04. The boot loader is now lubuntu. I know how to change the boot order & have done so but if I want to get rid of lubuntu, don't I have to change the boot loader back to ubuntu in order for my computer to boot up again.

[NikTh]

Boot from Ubuntu and give

sudo grub-install /dev/sda

[firekage]

Boot from Ubuntu and give

sudo grub-install /dev/sda

How would it look if i wanted to install it using UUID?

[wilee-nilee]

How would it look if i wanted to install it using UUID?

Your question makes no sense, the mbr sda has no uuid, and a uuid is not needed to load it, the uuid is basically for fstab.