Can't change volume or mute Sony headphones connected to Mac I use some Sony headphones on an iMac and they've been working well for around 4 months.

Now, I start up my Mac to go to Safari and listen to some songs. I realize that my headphones are a bit loud. I hit F11 on my Apple keyboard to lower down the audio and for some reason it won't lower! I can hit the mute button and still nothing will happen.
Try holding down the fn button, located at the bottom far left corner of the keyboard. Your keys might have somehow got switched up because I have found that if the buttons at the top do not work, holding fn and pressing the button makes it work