...
As soon as you do, the call will start and the toolbar on the top will change.
On this toolbar you can:
...
My video&audio on cursor — this setting shows your video stream next to your cursor on the board. It also means that if the second option(“Always play my audio to all participants”) is disabled, your audio will be played only to those who see your cursor.
Always play my audio to all participants — turning this on means that no matter whether someone sees your cursor or not, they will hear what you’re saying when your microphone is enabled. When turned off, only those who have your cursor within their viewport can hear you.
Microphone — select which microphone device you would like to use during the call.
Camera — select which camera you’d like to use during the call.
Add card with my camera stream — adds an element on the board where users can view your video. Your camera in the toolbar in the upper right corner must be enabled for this to work.
Add card with my screen share — adds an element on the board where users can see your screen. Once selected, the browser will ask you to select what you want to share and screen sharing will be enabled automatically. It’s necessary to add this card in order for others to see your screen.
...
If you want to present your work on the board during the call, click on your avatar and select Start presenting. 
As soon as you do, everyone on the board will get a notification asking them to follow you. Click Follow to start seeing what the other user is showing. 
You can also start following someone who’s not currently presenting. Click on their avatar and select Follow. Use it to see what they’re seeing when you’re not sure where someone is or what they’re talking about.
Another option is to ask a specific person to follow you. Click on their avatar and select Ask to follow you. Use it when you feel someone is lost and might need to refocus.
...
If you want to stop following someone, simply move the board to a different position with your cursor. You can also click on their avatar and select Stop following or click Stop on the board outline.
To stop presenting, click your own avatar and select Stop presenting. 
Video and screen sharing stream cards
...
To add a stream card:
Go to Power tools.
Click Insert video stream.
Select whose stream you’d like to add — the current speaker or a specific call participant.
Press Insert to add the card.
...
Share camera stream — changes the card to show the camera stream of the user (if they have their camera enabled in the top toolbar).
Share screen share stream — changes the card to show the screen of the user (if they have screen sharing enabled in the top toolbar).
Mute/Unmute this stream — enables/disables any sound coming from that card.
Add comment — add a note for your collaborators.
Lock — keep the element locked in place so it can’t be moved until it’s unlocked (also works with a shortcut CTRL/CMD + L).
...
