Webinar duration, Q&A and Chat options can be changed while the webinar is running.
If the Host Chats to all or individual attendees, the Chat icon on the attendees screen turns orange and a box highlights the message - this Chat is also seen by the panellists. You can't select individual attendees or a number of the panellists to chat to.
Powerpoint slide focus - when sharing slides the presenter needs to click on the slides to give focus back to Powerpoint, before being able to advance them using their mouse or keyboard.
As a Host, it can be useful to have a separate computer available with a personal account so that you can view as an attendee (don't forget to invite yourself), but this needs to be done via a different email account and zoom may automatically add you as a panellist.
If a user shares their screen but forgets to check the audio before sharing, the dropdown allows them to start sharing audio without quitting/re-starting apps ( ...More>Share Computer Sound)
Host can mute shared audio and stop sharing remote screens