1) Swapping QS or TS credits for lesser meal/snack credits is TOTALLY up to the CM.
2) There is no stated policy for the trade.
3) Your resort Concierge can usually do this for you, but not required to do so.
. . . since this is more of a "favor" to the guest, be nice when you ask
. . . it is just a matter of debiting QS/TS credits and crediting QS or Snack credits
. . . it takes 2-4 minutes at the counter
. . . once exchanged, it is permanent and must be accepted by any eatery concerned
4) The food location has the option of making a change, but are not under a mandate to do so.