I bought quart bottle of bleach-free "Mildew remover" in a boat-supply store (WM, BW, etc.). Forgot the name of the stuff, but I think it is green in color. (down't worry; it doesn't turn the fabric or vinyl green). If you diluted version of "Kitchen/Bath spray cleaner", and don't let it dry on the cusions, that should work too.
Capt Will, 2002 G/W 282 Sailfish, F225's
USCG Master, 50 Ton; Towing endorsement
Indian River, De
U.S.A.F. - 1965-1971