How to make Ubuntu be the main one on a black screen?

Question

linux

We have two OS Linux mint and Ubuntu, later I installed Linux mint, but I will use Ubuntu often... I want to be the main Ubuntu on this screen, not Linux mint, how can I do this?
For example, I will show a picture from the Internet, I used to have this.

Answer 1

In order for the hornbeam to find all the OS, you need to do:
Then, in /etc/default/grub
Find an urgent like:
And put the serial number of your OS in the list there (they can also be found in the same file below, counting from zero, as usual).

Answer 2

google: grub savedefault