Grub is the system which loads Linux. On startup, a menu offers options for booting the operating system(s) including various configurations. I am editing the loader to get Windows to boot
first on a dual-boot system. Another option is to adjust the menu timeout.
Firstly boot your own system and make a note of your current boot configuration, similar to the example above. There are a couple of options for editing Grub..
1. Use Grub Customiser
sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer
The Grub Customiser is straightforward to use and self-explanatory. Alternatively..
2. Edit Grub directly (backing-up its config file first)
sudo cp /etc/default/grub /etc/default/grub.bak
sudo vi /etc/default/grub
In the above example I am using sudo to raise the permissions level to perform these tasks. I am using vi as my preferred text editor.
To make Windows boot first, find the line that contains..
..and set it to the required boot line:
Note that the menu items are zero-indexed. This means that the first item in the list is 0 and the fifth item is actually 4. So to boot to the fifth item in the list (see top image), the line would require the number 4.
To change the Grub timeout, adjust the line in seconds..
Finally rebuild the updated grub menu after all changes..
The system should now boot using the modified settings.