First check what line Windows is on in the GRUB menu during boot.
Then from a terminal: (I assume you are root, otherwise put sudo in front of the command)
# vi /etc/default/grub
Find the following line, located almost at the top
GRUB_DEFAULT=0
Now if Windows was on line 3 on boot then change the line to:
GRUB_DEFAULT=2
(GRUB starts counting at 0 (zero) so always take 1 lower than the number in the menu!
Save the file
# update-grub
Now when you reboot the computer, the Windows startup line should be preselected in the startup menu.
So that Windows starts automatically if you don’t make a selection within 10 seconds.
+++++++
Change the startup delay ( Time that the menu is visible and you can make a selection)
# vi /etc/default/grub
Search for GRUB_TIMEOUT
Put the number of seconds you want there.
# update-grub
