Admitted as Undeclared - Humanities?

So I was admitted as Undeclared - Humanities to UCLA and I have a couple questions. Does that mean that I am only able to declare a major in humanities after two years? Or can I decide to declare a major in like Environmental Science or something at the end of my sophomore year. Of course it was in College of Letters and Science and I’m just curious but if I wanted to go to a different college like the college of film or whatever, would I be able to switch colleges at UCLA? Is there like an additional application that I can fill out after I’ve been attending for a while? I’m just confused as to how much freedom or how restricted I will be in declaring my major because I really have no idea what I want to do. Thanks so much!