Problem 1: The volume control on my laptop (Mac air settings up to date) does not work only when the headphones are in.
2.Problem: After a certain time, the sound of videos fails or the video is interrupted
I don't know how the Incognito Browser should help with your problem, but:
Normally simply via the menu button of the browser, the incognito mode is then displayed directly
Oh sorry, that was an old question that I haven't deleted yet