Firefox low volume on video playback

I am running Firefox on Mint Debian edition, I find the Youtube playback very low volume preset at about 1/4 of max, I try set it to the max but it returned the same after restart. I start FF in trouble shooting mode to disable theme and extension but didn't change thing, I remove and reinstall FF also did not help. I find something strange that, on the Help menu it said the updates disabled by system administrator but I did not do that, it is now on 116.0 64bits, any comment ?