Can't control volume for external monitor - "USB Type C Monitor "The selected device has no output controls"
I am using MacBook Pro 13-inch, 2017, Four Thunderbolt 3 Ports with LG 27UK850-W monitor. This monitor has built-in speakers and it works fine with USB Type-C cable but unfortunately it is not possible to control volume from System Preferences / Sound or keyboard shortcuts.
I've checked and saw some similar posts but couldn't find a solution. Is it impossible to enable these controls for external speaker?
MacBook Pro TouchBar and Touch ID, macOS High Sierra (10.13.6)