In QuickBooks, click on Customer Center. They will be displayed in Columns on the left. Right click on the the horizontal Title Bar; typically Name and Balance Total. Select Customize Columns, (Available Columns) scroll to the bottom and highlight AccountID, then click Add (Chosen Columns) to create a new column called AccountID. Click on OK.
You can now see which Customers have been bound to Accounts in your CRM (in Account Record - QB Full Name). If a customer is not bound, its typically spelling is different in both applications