Dell XPS 17, intel 11th gen, 9710, with KDE Plasma

Dear mates!
My laptop is only few months old but my left speaker broke and makes this awful sond. I try to keep it from the Settings / Audio / muted but after some short time automaticaly the balance changes and I start hearing it again.
My question is how to permanently mute the left speaker until I get it fixed in the future?
Thanks