disable start up sound - MacBookAir
I often work in the public library or after everyone is asleep at home.
The boot up sound on my MacBookAir is always intrusive.
How do I mute this permanently? I can't think of why I would need it in the future.
OS instructions please, I avoid uploading "stuff" from the internet.
Using OS X El Capitan Ver10.11.4
MacBook Air, OS X ElCapitan Ver 10.11.4