Before you start
This needs Heard about us switched on. An admin turns it on in Settings, under Features.
Step 1: Choose the answers
In the admin menu: Setup & help, then Settings, then Questions
The question is asked once, after a customer's first purchase. Add, remove and reorder the answers it offers, then click "Save". An answer cannot be renamed, so past answers keep their meaning: to change a wording, add the new one and remove the old.
Step 2: Read the results
In the admin menu: Marketing, then Heard about us
Each answer shows how many people chose it, counting answers given after a purchase and on a registration form. Change "Period" and "Answered" to narrow it. An answer the question no longer offers is marked "no longer asked" and keeps its count.
"Who answered" lists each person, newest first. Click an answer to see only the people who chose it, and a name to open that client.