Thank you very much for your helpful reply Treeoflife.
Yes, English is not my first language unfortunately, I wish it was. I haven't mentioned it yet, I will start mentioning. You are right it may help. I think many academics are of course perfectionist as it is what job requires. So I understand their feedback. It is my fault.
Thank you very much for the website, I will work on it now. Yes, I have made an index page of all the points for slides. I will read through all the tips and construct whole presentation again.
I was worried about it will start correcting small errors. Thank you, it will look better and make me feel more confident about my applications too. They wont know.
Hope your PhD is going well.