How to level the volume sounds

Hi again,

Now that I’ve finished the project I need to level the volume sounds of all the songs.
Is there a way to proceed?

Thank you,

Apply the ReplyGain plugin to each song.

Thank you,
Alternatively, can I adjust the volume by modifying the “Amplify” effect of each song?

Yes, but making them look similar amplitude will not necessarily make them equally loud,
as human hearing is not equally sensitive to all frequencies,
see … Equal-loudness contour - Wikipedia

ReplayGain includes an attempt to correct for the peculiarities of human hearing.

Ok, I’ll try.