How do I change how my documents look — my logo and accent colour?

Business appearance shows a sample quote, invoice or email, marked Preview — not sent, so you can see your logo and accent before anything reaches a customer. Your whole logo shows, never cropped or stretched. The accent is a single color: it draws the line under your letterhead and under your quote page's header. Your emails use it for their button only when white text on it is easy to read (4.5:1 or more); otherwise that button is DeskOps teal. The accent has to be dark enough to read on white paper, and the pay button on your invoice page stays DeskOps teal. Changing it never touches an amount, tax, deposit or term. Quotes you have already sent keep the look they went out with; invoices use your current logo and accent each time one is opened or sent.