The online S2722DZ User's Guide page 48 shows Menu--> Audio & Webcam--> Speaker --> Mute or Unmute. Did you try changing that to Mute?
Hello community, I have an issue with my S2722DZ monitor. I have connected my external speakers to the Audio line-out 3.5mm port and the speakers are working. But, the built-in speakers are still playing and that's really annoying. In the OSD menu I didn't find an option to disable them. A firmware upgrade didn't help either. I can't connect the external speakers to my PC, as I have two PC and don't want to switch the cable every time. With my former LG Monitor that setup was working flawlessly. I hope we can sort this issue out, otherwise I have to return the S2722DZ and stay with my LG.Best regards
S2722DZ, disable built-in speakers while using Audio line-out?