More formal word for "know-it-all" was closed as duplicate of Know-it-alls--a synonym, which is duplicate of Is there word for this, other than know-it-all?, which is duplicate of One word for someone who thinks they can do anything, and believes everything they do is right but others are wrong.
I understand that there are many words and phrases that can be used in place of know-it-all. But the question doesn't need to be closed because
- It has a very specific context.
- It is seeking a more formal word than know-it-all. There is no answer in any of those questions that say which word or phrase is more formal than others.
- The OP is explaining why the question is not duplicate.
I think this question reads far better than a majority of questions that are not closed on ELU. Can we just reopen the question and let the OP get an answer and move on? Is closing it the best thing we can do about it?