The setting is important when exchanging order data with your integrated CMS platform.
If you have multiple unconnected stores with different customer/orders bases, then the order IDs in the stores will be different. Therefore, when transferring an order from one store to another, you must reset the external identifier so that the order in the new store is displayed as a different order.
If you have stores that are both connected with each other and have a common order base, there is no need to reset the external identifier.
When the setting “Common external order identifiers for all stores” is enabled - the external identifier will not be reset for the order when changing the store.
If the setting is disabled and orders have the same external identifiers (but in different stores), a message will appear informing you that the external identifier will be reset upon changing the store.
With the setting enabled, if the external order ID was already specified for this store, the order will not be saved. The following message will be displayed: “The external ID of the order already exists in this store”.