Close the 'Edit Music Database' window, and all functionality in the 'Quick List' will work. If you wish to view the Music Database while the Quick List is also displayed, use main menu option 'Music | Load from Database'.
In case you're wondering why the program behaves this way, it is because when you're in 'Edit Music Database' mode, all changes made in the music player (i.e., changing tempo, pitch, bpm, rating, loop markers or other markers) immediately update the current record in the music database. If I allowed the quick list or history list to change the currently loaded music, it would screw up how the 'Edit Music Database' works.