in the preferences "display" tab under "environment options=, theres a setting called, open song with reverb, vol etc. which needs to be checked.

If you created and saved your songs with different volumes etc. while this option was disabled, you have to first enable this option, then load your song and save again (for all songs created unfortunately).

For new songs, make sure this option is enabled first and always, then your songs will always load with the correct volume settings per song.