if an order has location x and one inventory item is out of stock during fulfillment can i change the location on the item fulfillment?

A fulfillment can only be from a single location. But you can issue multiple fulfillments from the Sales Order and define the location on the fulfillment.

Thanks. I have an order with 3 lines. 1 is no longer available in the location that;s set on the order. In fulfillment, I changed the location at the line level to a location that does have stock, but it doesn't do anything, as in, save.