Each Aqua Schedules customer should be synced with a QBO customer account. Navigate to the Customers Tab, select the customer you want to sync from the list and then click Customer QuickBooks Link. You'll see a drop down list that you can use to link to an existing customer account. If you don't currently have a customer account in QBO you can click the green button Create New Customer Account. This will generate the account for your in QBO automatically and establish the link.