If more than 4 group members sign in for an online session, the excess members automatically become bystanders. It is also possible for a member to sign in as a bystander if another member has already opened a session. In addition, an active player can turn himself into a bystander. To join a game as a bystander, you can do the following:
Press this button on the app bar of the game view to show the list of secondary commands. On a PC, you can use the menu of the title bar alternatively. This menu is more detailed than that of the app bar, so you can reach almost all the panes directly.
Press this button with the signature "Join bystander" if you want to attend an online session as a bystander. However, another member must have already opened a session as game master. If you are already an active player, you can switch to the spectator bench by pressing this button.
With this button you can leave the online session at any time. You can also leave the session by pressing the corresponding button on the app bar.