For live Q&A, there're three usertypes:
Moderator who starts the meeting, moderates chat, questions and polls and take requests from participants to ask questions via audio.
Speakers can answer questions.
Participants can ask questions by requesting audio so moderator can let them ask their questions.
Important: Speakers have to leave the live Zoom/Webex meeting to join the live Q&A on the website on the website. If not, both livestream and Q&A would run at the same time. Live Q&A session should be started once the main session is over.
