Go to Applications > Utilities > Audio MIDI Setup
Haha this is still happening on one of my old eMacs sometimes! It has 10.4 installed! But it hasn't happened for a while now anymore, I should try to figure out what I've changed.
I have never had this issue on newer Macs, such as my iMac (mid 2011, OSX Lion - Mountain Lion - Mavericks) or my Mac Pro (mid 2010 - OSX Mavericks).
Yeah I understand that. But to be honest, if you're using your iMac professionally, you shouldn't have updated to Yosemite in the first place. It probably hasn't to do with that, but Yosemite is full of bugs and full of crap, and most Pros have kept their fingers away from it. Only crazy Apple bootlickers have installed this on their Mac.This is very weird behavior because i have iMac 2012 and newest Mac OS X Yosemite
And anyway there is more than this one bug which makes my workplace very unused...