You can link multiple devices together using Sessions, so when you turn pages on the master device, all connected devices will stay in sync. Sessions requires WiFi is on and the device is connected to the internet.
From the sidebar, open the Sessions tab.
When you choose Start New Session, the header changes to green to indicate you are in control of a session, and others can join your session.
On the master device, you'll see a list of all devices who have joined your session. Enable Allow Control to give that person access to controlling all devices. Your header will turn red, and the new device in control will have a green header, but you can still close the session; the "controller" cannot.
When you Connect to a Session, choose the device you'd like to join.
You have successfully connected when your header turns red. Any actions made on the master device will be shown on your device. If you are logged into the same account as the master device, your device will even refresh when new annotations are made on the master device.
Disconnect at any time to gain access to your own device again.
Control Indicators in PDF View
The PDF view doesn't have headers, so to know if you are controlling a session or are connected to another device, there are icons at the top right.
The green icon has an arrow going away from it, indicating your are the master device controlling the session.
The red icon has an arrow coming toward it, indicating you are connected to another device.