How does John Proctor behave towards Danforth during his questioning in Act 3?
If we have a look at this intense scene, we can see that throughout (until the very end), John Proctor is very respectful of Judge Danforth and recognises his position of authority and importance as a person. He calls Danforth "Sir," for example, and gives straight, matter-of-fact responses to the questions that Danforth asks him. Even when the focus of this scene moves to Proctor himself and his claim that Abigail Williams is a harlot, he still maintains this attitude of respect and deference. Consider that he responds that Elizabeth cannot lie to Danforth's question asking whether she is an honest woman:
In her life, sir, she have never lied. There are them that cannot sing, and them that cannot weep--my wife cannot lie. I have paid much to learn it, sir.
Note the repeated use of "sir" throughout this speech and throughout this section of Act III to refer to Danforth. It is only at the very end of this scene, when John Proctor sees the true nature of the "justice" in Salem, that this attitude is lost. Apart from this one section of the scene, John Proctor presents himself as a man who is deferential towards the authority of Judge Danforth, and very respectful towards him.