Adjust stock (batch): tap Adjust stock up top → every row gets an input; type + or − amounts (e.g. 40, or -3 to reduce) across as many products as you like — entries persist as you search/filter. Tap Review for an overview, then Confirm & apply to write to both platforms. Hold is the simple stepper: step to a number, tap to confirm — it lowers ONLY online (Shopify) availability and leaves Square physical alone. Live — both "Confirm & apply" (stock) and Hold write for real to Square/Shopify and show the read-back.