Sep 13 - Buenos vs. Buenas: Which one to use?

Can someone please tell me if one would write

"Buenos días, señorita"

or

"Buenas días, señorita"

Or does the use of "Buenos" and "Buenas" depend on the word directly after it?

Being either "días", "tardes" or "noches"

and not if your putting "señor", "señora" or "señorita" at the end?

Thanks for the help!