I have an uncle who thinks he knows everything and if he disagrees with you he goes on and one and one about it until you have to agree with him just to shut him up.
Queenie, how do you deal with someone like that?—Screaming inside
Well, you can just ignore him. Or you can agree with him, as you said – just say “Yes, yes, of course” and then change the subject or just walk away.
Or just do not talk to him about anything controversial – although I would bet if you said, “What a nice day it is!” he would start getting on about how it looked like it was going to rain, in which case you could ask to borrow his raincoat and umbrella (and then have to listen to him get on about how foolish you were not to bring your own!)
Better yet, try to have as little to do with him as possible.