The bulk editor lets you simultaneously modify multiple products and their variants from your Inventory listing page. The bulk data editor appears as soon a you select one or more products from your listing. The Bulk Editor allows you to edit all properties of your product variations. Note that only a predefined set of columns is visible by default, you can change that by viewing more columns as shown in the animatio below.
You can copy a field value to adjacent cells by hovering over the source input box. A blue button will appear at the bottom right corner. Drag the blue item to get the value copied over to the target input boxes.