From the Settings>Accounting page, click the "Add accounting integration" button as shown here:
Next, click “Connect,” sign into your QBO account, and follow the prompts.
When your QBO is successfully integrated, you will see it on the Accounting page:
If syncing is OFF, you'll need to manually enable it by following these steps:
By taking the steps mentioned above, you will be all set for syncing, whether that's our daily automatic syncing, or manually syncing Purchase Orders and invoices.