The first ten minutes, from opening the app to a change you can see in your store.
1. Open the app
Open metangelo from your Shopify admin, under Apps. It opens on Home, with a card each for Products, Variants, Inventory and Orders.
2. Say what you want to edit
Press Edit variants (or Edit products, or Edit orders). The first time, Shopify asks in its own window whether the app may read that part of your store. Allow it. If you refuse, the card says why and offers Allow reading variants; nothing else changes.
3. Choose fields
Choose fields lists Shopify's own fields above your store's metafield definitions, each with a checkbox. Tick the ones you want as columns, then press Show N fields. See Choosing the fields to edit.
4. Edit in the grid
Rows are your variants (or products, or orders), a page at a time. Type into a cell and leave it: the edit is kept as a draft. Paste a column from a spreadsheet, or drag a value down. See Typing, pasting and filling down.
5. Review and apply
Press Review N changes. Each draft is listed with the value in your store now and the value after you apply. Press Apply N changes. The first time, Shopify asks whether the app may edit your store. Allow it.
6. See it land
The result page counts the rows as they are written, then shows each cell with what happened to it: Updated, with the value read back from your store. See What happens when you apply.
Changed your mind? Revert these changes on that page puts the values back.