This article describes the steps to change the primary contact of an quote/order by using the contact card tool.
1. Select the quote/order where you want to change the primary contact.
2. Select contact card and can see the list of contacts including primary contact already assigned if any.
3. Select the contact where you want to set it as primary contact.
4. Click on the button and that will the new contact as primary contact and it will void the previous primary contact as just contact.