I'm having issues with quantity changes in the gold shops. In The Bitfrost I had purchased some rawhide leather at a quantity of 15. However after I pressed continue shopping and bought an item such as a formula, the quantity is still 15 and could not lower it back to one, the quantity was fixed. I could only adjust the quantities on items such as the rawhide, fruit stones, and lyre. I ran into the same problem of fixed quantities when I was in Barton Boutique. One item asked for alchemy was The Gift. The only way to get the exact quantity needed for the formula was to purchase it 50 times, being unable to adjust the quantities.
It has never been set up to allow for the purchase of multiple quantities of a single item for most items in the gold shops. Chances are it was only set up for the components in Bifrost because (from what I understand about Alchemy) multiples are generally needed to craft a formula.
The problem is in Bitfrost then. You can edit some of the quantities, but I've had some items that lock in as set quantities that I purchased previous. Such as if I were to buy 5 medicinal herbs and by a formula after that. The set quantity will show as me buying 5 formulas.