Here are some tricky parts: 1) When using Firefox, take YouTube video as an example, I can hear the music if I connect my laptop to '''an external Bluetooth speaker'''. (But without using a Bluetooth speaker or any external speaker, there is no sound through '''my laptop''' even thought I turn my laptop volume to the greatest.) 2) For the same video, if I use google chrome, I have no problem hear the music no matter using a Bluetooth speaker or my laptop internal speaker. 3) You can argue my Firefox privacy Autoplay setting was wrong. But I checked and I allow both audio and video for all websites. Besides, I also checked the Permissions status on each website. 4) The weirdest part I don't get: Supposedly I can play and hear sound through Firefox, since I authorize all the website. But why there is no sound if I'm using my laptop's internal speaker? ( And only the laptop's internal speaker) 5) For my internal speaker, it work fine when I use Zoom, hear music through windows' Groove player, or even play video through Chrome. Last but not least, I still ran troubleshooting trying to fix my internal speaker. But they can't detect any problem. I'm so confused.... Does firefox hate my laptops internal speaker? Please help me. Thanks