The graphical way as mentioned before:
http://ubuntuhandbook.org/index.php/2014/04/install-grub-customizer-ubuntu-1404/
The Application is not in the Repositories of your Software Center by default. That's why you need to add a Personal Package Archive (PPA) and update the sources.
Hit Super/Win to open Dash, type soft and choose Software & Updates. Go to Other Software and click add. There you can enter the new resource ppa:danielrichter2007/grub-customizer. After confirm and close you would be asked to reload. Now you can search for in grub-customizer in your Software Center and install it.
Without clicking, you can install it in your terminal (CTRL+ALT+T)
sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt update
sudo apt install grub-customizer
Or just change boot order in grub config on your own.
All of the following commands need sudoers permissions. You can hit ALT+F2 and type gksu (maybe not installed by default) in front of every command or open a terminal with CTRL+ALT+T an use sudo to run commands with needed privileges
First of all backup the old config with
cp /etc/default/grub /etc/default/grub.bak
then open the open grub file with your favourite editor e.g. gedit
gedit /etc/default/grub
or directly open it within your terminal with vi or vim (if you know how to use)
vim /etc/default/grub
and edit the GRUB_DEFAULT Value to the item you want to select by default (counted from zero), save the file an run
update-grub
After that a new Configuration is built and you can reboot to test.
Multiple Q/A:
How do I change the GRUB boot order?
Good that you already solved the part of switching from Windows to Linux.
The other direction is not that hard:
There is the command grub-reboot that does just what you need - see below for detais:
If your grub menu entry for the system you want to boot is "Windows", you would just do:
$ grub-reboot Windows
If you configure the hardware to boot after a power failure, I see no reason the computer could not just stay running.
But if not, it should be possible to wake it up with wake on lan (WOL), booting the system you configured before shutdown.
The WOL works with "special" network packages that can not be routed outside the local network, so there is a device needed in that network, like a some DSL router or any computer.
From man 8 grub-reboot:
GRUB-REBOOT(8) System Administration Utilities GRUB-REBOOT(8)
NAME
grub-reboot - set the default boot entry for GRUB, for the next
boot only
SYNOPSIS
grub-reboot [OPTION] MENU_ENTRY
DESCRIPTION
Set the default boot menu entry for GRUB, for the next boot
only.
[ ... ]
--boot-directory=DIR
expect GRUB images under the directory DIR/grub instead
of the /boot/grub directory
MENU_ENTRY is a number, a menu item title or a menu item iden‐
tifier. Please note that menu items in submenus or sub-submenus
require specifying the submenu components and then the menu
item component. The titles should be separated using the
greater-than character (>) with no extra spaces. Depending on
your shell some characters including > may need escaping. More
information about this is available in the GRUB Manual in the
section about the 'default' command.
[ ... ]
Run man -k grub for a list of related command - eg. grub-set-default may help you too.
Best Answer
The default menu choice is (or can be) stored in the GRUB "environment block", a little 1024 byte file that lives in /boot/grub/grubenv by default. You could easily put that on a drive accessible from both Windows and Linux (e.g. a FAT or NTFS partition) and modify it accordingly. I've done this already one-way (Linux -> Windows) for my mother's laptop using a little script:
Also added the following to /etc/sudoers to make the necessary commands execute without prompting:
Alternatively, it looks like someone may already have done the heavy lifting:
http://de.mcbf.net/david/grubchoosedefault/
Haven't tried this yet though ..