Without needing any additional software, the grub boot order can be edited via command line.
Changing the boot order won’t modify the OS list, but will set a different OS to booy by default.
Before you modify the /etc/default/grub file, create a backup:
$ sudo cp /etc/default/grub{,.bak}
To modify the boot order, edit the /etc/default/grub file, with root priviledges:
$ sudo vim /etc/default/grub
Find the line: GRUB_DEFAULT=0.
0 (zero) represents the first OS in the list, 1 represents the second OS in the list, … 4 represents the fifth OS in the list. Replace the number written after GRUB_DEFAULT= with the number representing your desired OS.
To apply the changes, update the grub menu:
$ sudo update-grub
The update-grub command updates the /boot/grub/grub.cfg file.