Back when I was distro hopping after I became dissatisfied with the operating system that I was using, it was not uncommon for me to have two, three, or even four operating systems on the same hard drive. An incident occurred at the recent Installfest on the 3rd of December that brought to mind a a small application that I had used to change the default operating system, Grub Customizer. If you have two or more operating systems installed on the same hard drive it is possible to use Grub Customizer to change the default boot order. When you install a second Operating system, it usually becomes the default one (the OS that will boot if you take no action during the Grub display). I used to change Operating Systems frequently so the default one would change every time I installed a new one. Today when an individual wants a dual boot system with Microsoft Windows and we install a Linux system for him, it becomes the default boot system. If that individual still wants Microsoft Windows as the default system, you can change the boot order from the command line or you can install Grub Customizer.
sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer
Once installed and you launch Grub Customizer, you can change the boot order with several clicks of the mouse. Merely select the item that you want to move up to the default boot position and use the up arrow to move it to the top. You can also change the number of seconds before the computer will boot the default on the second tab. After you have made your changes you simply save the configuration and close the application.