There are no such things as "stupid" questions. However if you think your question is a bit stupid, then this is the right place for you to post it. Please stick to easy to-the-point questions that you feel people can answer fast. For long and complicated questions prefer the other forums within the support section. Before you post please read this
It is much easier to edit the default value as demonstrated in the thread referenced by hsoltau. You open the menu, change one number, save the changed menu and close the terminal. What could be easier?
Of course the listing order in the Grub menu isn't changed, but the OS you choose will boot by default from where ever it is in the menu.