What happens when I click Approve (mark paid) on a bank transfer order?

Approve (mark paid) confirms you've received the money. When you click it:

• The proof is marked approved
• If the order was Pending or Awaiting Verification, it moves to Processing
• In that case, stock for the order is also reserved if it wasn't already
• The payment is recorded as fully paid, and the reference the customer entered is saved on the order
• When the status moves, the Timeline shows "Status changed from Pending to Processing — payment proof approved"

An order that's already further along, like Shipped, keeps its status. Check your bank statement before approving, because there's no undo button.