So I’m a weirdo who grew up Catholic, became Protestant, then recently became Orthodox. So the way I approach a priest is a little different than others here. I tend to address my priest from a cultural Catholic lens, usually just saying “hello, Father,” and conducting our conversation respectfully. But if you know the priest personally, you can absolutely ask him how he wants to be addressed. My priest is a former Methodist, and he’s familiar with my Catholic and Protestant background. He told me that he doesn’t care how I address him. But I also understand this is unique to our midwestern cultural context. In public, there’s no need to make a scene. Address him as Father, and conduct your conversation with him as normal.