Begin using application with configuring your company. Navigate to Settings section.
Check that the information there is accurate, fill in the missing fields, and optionally upload your company logo.
Scroll down to the address section, and make sure it is correct. This address will be used to form From field on the coming invoices.
Next section will give you control over how invoices are created. First 3 fields will define how invoice numbers are generated. You can specify the starting invoice #. By default, invoice numbers are prefixed with "BSA", but you can change this to any other characters, or leave it black to disable prefixes. Same thing goes for invoice suffix.
Default Tax Percent is the company-wide tax that will apply to invoices, unless client-level custom tax was configured in client's settings.
Default Net Terms will apply to invoice, unless custom value is specified in client settings.
Hide Zero Discounts options will hide discount line items during invoice print or export, if the discount is equal to zero. This could be useful if you do not plan to give your customers discounts on second searches of the same type.
Invoice PDF Template will change the layout of the printed invoice according to the template. You can preview the templates using "Preview Template" button.
QuickBooks Online Integration
To setup QuickBooks online integration, please read How to integrate QuickBooks Online