If there are open purchase orders (with old FX rate) receipted in after a FX rate change, GRN is changing the FX cost to keep the NZD cost the same.
We need the FX cost to remain and same, NZD cost can update as per the new rate.
For example, PO# XXXXX was sent in April when USD FX rate was 0.58 and now we have updated the USD FX rate to 0.65. If you receipt in this order, JIWA will update the FX cost from $4.30 to $4.82, keeping the NZD cost of $7.14.
I suspect a setting (e.g. Update Suppliers Cost or Update Home Landed Cost), but I'm not sure which one, and I don't want to ask the customer to experiment.