To access this feature, you must be on Goodshuffle Pro Standard or above.
The sales lead will show on your projects at the top of the Quote/Invoice
If you're not seeing this on your quotes/invoices, you can check your project settings (the gear symbol next to 'Send to Client') to see if you've got 'Show Sales Lead' deactivated.
Need to change the Sales Lead on the project? Click here to find out how!