The Bulk Edit tool allows you to edit values on up to 10 Custom Fields at once. This allows you to skip the spreadsheet and make bulk changes right in the app.
You can access the Bulk Edit feature on Products, Customers, Orders, and Collections by hovering over their menu item and selecting Bulk Edit.
From this screen you can select which Custom Fields you would like to edit, you can search for products to edit, and filter by SKU and Shopify Vendor. Click search to begin Bulk Editing.
If you didn't search for a specific product, you will now have the ability to edit all of your Custom Fields in a cell-style editor, similar to Google Sheets or Excel. Use the down arrow in any cell to copy the data down through all cells below it.
After you finish editing your fields, click 'Save'.