What to do when someone is not able to make you understand something

If you understand that the presenter is not able to make you understand whatever is that you are asking him…don’t push the presenter further, coz it is not a game that you are going to win (applies to both the presenter and the questioner), instead it’s an argument that you are firing. As a questioner, you give the presenter some space to escape and get back to you later on what you want to understand, and you don’t make a point that goes like I-caught-you. 

The point you make as a questioner: what I don’t understand and why is it important for the presenter to get back to you after the presentation. That’s it, don’t push it further. And, the point you make as a presenter: either the thing is out of scope or you don’t understand his question, or accept the fact that you don’t have an answer to his question and you will get back after you have one (if required, accept to the questioners point if he is damn sure about it).

The point is, if you understand that the other person is not able to make you understand something, give him the benefit of doubt and wait for the answer after the presentation (sometime later). And do not push anyone to a level that can make them feel jittery when giving a presentation or a talk.