Video from source file and cleaning up css files

Hi Gridbox team.
Have 2 questions:
1. I face the problem with video from source file.
It's always mute. Sound has to be switched on manualy when play.
2. How to clean up all custom settings done for desktop, laptop, tablets and mobiles, Is there any place where I could clean it just with one click to make everywhere same settings like on desktop?

Thank you

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