What is the Primary Device
The first device to join the game will be marked as the Primary Device and, by default, is the only device that will be able to navigate the main menus. The Primary Device is denoted by a glowing aura around its device flag. When the option [Options > Gameplay > Anyone Can Control Menus] is enabled, all devices act as the Primary Device except when a device has been disconnected.
By default anyone can pause the game. This can be disabled in the options menu. [Options > Gameplay > Anyone Can Pause] Whenever the game is paused, the Primary Device and the device that paused the game can control the pause menu.