Add notes for customers
Go to Sales, then select Customers.
Select your customer from the list, then select Edit.
Select the Notes tab, then add the information in the field.
Select Save.
For more information click here: https://quickbooks.intuit.com/learn-support/en-us/list-reports/add-and-use-notes/00/186020
Regards
Rupinder Kaur | Sagenext