I am very much a noob to linux but not computing. I installed 22.04 LTS on an iMac 27 late 2015. I initially had issues with no sound at all. I dug through many videos and threads. I have the sound working through the Sound section in Settings most of the time.. I can test right/left and get a clear voice occasionally. One time for about 2 minutes I got video sound but then never again. I am trying on youtube and non-youtube sites. I have done the alsamixer adjustments based on many suggestions with what seems like very little success. I really don't know where to go from here.