Step 1:

Go to Orders > Order Detail > Click on Add Inventory Mapping or Change

Step 2:

Click on Select, and the confirm message below will be showed.
 

Step 3:

Select if the changed mapping only effect on only one order or all orders in New status.
 

Note:

 

If you choose Effect on all New orders, and change the mapping too, please note it means the mapping of Items with the same SKU (same store) and orders with mapping only applied to its own will be changed too.