Via FTP tool: Just replace the fullwidth-audio-player folder.
Via WP admin: Deactivate the plugin and delete it. Then upload the new zip and activate the plugin again.
In both cases you will not loose any of your created tracks/playlists and options.
The meta box in post/page is removed, you can now build the shortcode in Fullwidth Audio Player/Options/Shortcode Builder tab.
Now you find the new options in the Audio Player tab to use the Pop-Up feature and the other new features.
Go to the General tab and set the dimensions for the grid and list images. The default values are: 100×100 (List) and 200×200 (Grid).