Sony Airpeak S1 Help Manual page 67

If you want to switch the main and sub controllers, turn off one of the remote controllers, and then change the settings.
When you reset [Operation mode] to [Single] on the main controller, the sub controller becomes disconnected from the aircraft.
Related Topic
Selecting the operating mode of the control sticks
Attaching a mobile device to the remote controller
Linking the aircraft and remote controller
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