This is an annoying thing about any sport or activity. As soon as someone sees you are "bad" they immediately jump to give you advice. This can be all the way from "Keep your head down" to "Here's a ball, hit another one, and try to do this thing this time."

I don't care if you're a certified PGA Professional and Coach, trying to fix a swing in the middle of a round is never going to be helpful. I have no idea why people are so quick to do this. Even complete strangers will do this at any sign of a bad shot.

Yesterday I was on the range, and the range attendant who, by his own admission, "never really played golf" offered me advice that he "overheard an older gentleman tell his son". Literally the least qualified person by his own admission and he still tried give me unsolicited advice.

Rant Over. My response now is always "I'm working with a professional on a very specific drill and swing thought. I cannot introduce any other changes right now." I first said it because it was true, but now I say it because it works to get people to stop.