Copyright should be automatic when you create something. (Baring it's not illegal or infringing on other copyrights, haha.)
"Copyright is secured automatically when the work is created, and a work is “created” when it is fixed in a copy or phonorecord for the first time." - via www.copyright.gov/circs/circ01…
(ctrl-f "automatic" or go to page 3)
Whatever license you apply to your works is irrelevant to you. You have the copyright, you can do whatever you want with it. It's only other people who you're controlling permissions for.