Go to the main interface, find out and click the "Options" button. You can change the output quality settings by changing output formats, sample rate and bit rate as you like.
Also, we highly recommend that you convert Spotify music to M4A files format with 320 Kbps and the MP3 with 320Kbps to get a better sound quality.
What's more, TuneFab Spotify Music Converter for Mac allows users to manually adjust the sound volume of the output file. Just click to "Options" >"Advanced" then you can change the sound volume by yourself.
Related Article: More Advanced Settings of TuneFab Spotify Music Converter