For the advanced setting part, there is provided to select the location to update your inventory.
1. You can choose the location that you wish to add or update. So the add and update process would NOT apply to all the locations. It's provided in add product feed and update product feed.
Note: By default, the inventory location will be the Primary location that you set in the Shopify store
2. If you are unsure of the location that you selected, you can turn on the Auto Select Location toggle where it will auto-select the first inventory location found if the selected inventory location is not available.