defensive

Hey everyone, I'm kind of struggling with my bird as he's kinda aggressive when in his cage. He won't let me change his water and food without hissing and threatening to bite, and touching him/trying to make him step up when inside his cage is a big no no, he won't let me do that but bite me...

I have an approx. 1.7 year old Blue Crown and there are defensive behaviors in certain situations that I have questions about the normality of and how or if I should deal with. Generally, he is not an aggressive or hard-to-handle bird (to his "flock" members); He does occasionally play "rough"...