Can second that quantity options seem to be buggy.
Upping the quantity for selected items worked for quite a time - and I don't know if something in the game itself broke it and changed the address refering to or anything.
But right now there has been only one time ever since where I could change the value like I did before.
I can see in the editor that it changes an amount by the value entered in the trainer option - but couldn't find the value in the game itself nor does this value change at all after having selected another item.
on my machine I can't even get that option to enable.