Why does my song sound loud in Garageband, but not as loud when I export to .aif file?

Hey all,

I'm completely new to Garageband.

I have some recordings of my basement band from 1979 that a friend of mine transferred from cassette to CD many years ago. Recently, I have dragged one of the songs off the CD into Garageband to correct some volume fluctuations (my friend that did the cassette recording in 1979 was playing with the volume input when doing the recording). So, I've gotten all the volume fluctuations fixed, but now I'm ready to export the song to a new .aif file and I'm noticing that the song sounds much louder in Garageband, which I prefer, than it does when I play the .aif file on my Apple Music player. I want them both to sound the same volume when listening in Garageband and when I play the .aif file in Apple Music player. What am I doing wrong, and how do I get the volume louder on the finished .aif file? I haven't touched the volume control on my Mac, so I am wondering why this is occurring?