Auto GAIN - how to see that the sound is amplified?

how to see that the sound is auto amplified? And how many dB?
Button "gain" is always in the same position.
"Track analisis GAIN" and "read track GAIN at load" switched differently - does not change the position of the button, but heard the sound level changes.
PS - found in the playlist "Gain", but why when you play a track, the button "gain" on the mixer does not change.
Why two buttons "Gain" in software(1 in playlist, 2 - mixer), are not in sync with each other?
Button "gain" is always in the same position.
"Track analisis GAIN" and "read track GAIN at load" switched differently - does not change the position of the button, but heard the sound level changes.
PS - found in the playlist "Gain", but why when you play a track, the button "gain" on the mixer does not change.
Why two buttons "Gain" in software(1 in playlist, 2 - mixer), are not in sync with each other?