You can only edit them 1 at a time, could be something the OP can add in a Mass quantity change for all items . The maximum isn't 999 its actually 1,023 and you can make more of the same item in multiple slots and they will stack ingame. Thats why summoning KOS-MOS isn't an issue anymore since we can have over 1,000 Legendary cores thanks to this editor no more repeated trips to the editor when we run outhow do i change all the collectibles to 999? do i have to do them one by one....?