Spanish language Q&A Forum

Hi!! I would like to ask a question. So I'm doing a presentation in Spanish and i want to use the present perfect subjunctive in the last sentence. I want to say "I hope you enjoyed my presentation". The dictionary says that it's "espero que les haya gustado mi precentación", but isn't "haya" the verb form for "usted" and not "ustedes"? Several people are going to listen to me, so I want to address them all. What do I say? Is it "espero que les hayán gustado mi precentación" or "espero que les hayáis gustado mi precentación", or is it the sentence I wrote earlier?

Thank you in advance!!

I was recently given this sentence: 

Eugenia (entender)  ______ que no podamos ir.

I got it correct and know the form of "entender" to be used, but I have a side question: Why is "podamos" in the subjunctive here? Why not the indicative?