If your item has a bid it cannot be changed. If it does not have a bid you could change it back at least it used to be that way. If no bids are on the item cancel the auction and start again. You should be getting 50 free auctions a month.
PS: Glad to see you're still around. :-)
It's a fixed price auction. I had a quantity of 12 and have sold 2. I guess the "no change back rule" applies to fixed rate with bids as well. Listing was free. Free is good. Did you know if you go to your seller dashboard (My eBay Account Seller Dashboard) it shows you your total eBay sales from the beginning of time? Damn I sold a lot of stuff back in the day. Got your Christmas tree up?