Let’s say you have Ubuntu and Windows installed side-by-side, and you usually use Windows. By default, Ubuntu is the first option, so you have to scroll down to select windows every. time. you. power. on. your. computer.
Might as well try to change the order once and for all. To do this, install a little program called Startup Manager.
sudo apt-get install startupmanager
Once installed, you can run it from System > Administration > StartUp-Manager
From there, check out the dropdown under “Default operating system”