How do I Display Total Hours in Time Detail Section?

If you would like to see the Total Hours billed within the Time Detail section of an invoice, head under Invoice>Settings>Flexible Templates

Open the Flexible Template you'll be using for the relevant Client-Matter, and click on the Time tab. Ensure 'Include Time Summary' and 'Hours' checkboxes are enabled.

Total Hours should now appear on the Time Detail section of the invoice.