audio volume

Unity Engine
1

audio.PlayOneShot(pickupSound, 8.0);

audio.PlayOneShot(pickupSound, 1.0);

when I play it set to 8 or to 1 the volume is the same?
How can i make so the volume is louder?

2

I think 1 is max. AudioSource volume goes from 0 to 1.

3

Externally to Unity only. Daniel is right.