A method for using a multi-stage in-air hand gesture to adjust volume at a pair of smart glasses and control a user interface of an application. The method includes causing display, at a pair of smart glasses, of a user interface for an application. The method further includes receiving data from a multi-stage in-air hand gesture from sensors of a wrist-wearable device and determining that the user is performing a pinch gesture for a threshold amount of time and a wrist-rotation gesture in a first rotational direction while the pinch gesture is maintained, and based on this determination, increasing a volume for speaker output at the pair of smart glasses. The method further includes determining the user is performing another pinch gesture for less than the threshold amount of time, and in response causing performance of an operation at the user interface for the application while maintaining the increased volume.