LinPlug Spectral - Manual (Page 89)

Spectral will select the matching Oscillator and Filter.
Always Save to My Sounds means that whenever you save a sound
Spectral will open the “My Sounds” bank for saving in there. Of cource you
still can choose a different bank to save to, but the next time you save a
sound it will suggest My Sounds again. If the option is turned Off however,
you will always be suggested the last used bank to save to.