https://support.docusign.com/en/guides/ndse-user-guide-access-code

I don't know of a way to password protect individual documents with DocuSign, but you can add an access code to protect the envelope.  Is this what you're looking for?  There are also some account settings available that let you control whether you want the recipient to enter the access code only once or every time the recipient accesses the envelope.

Hi,

Where can I find the option that let me control whether the recipient should enter the access code only once or every time the recipient accesses the envelope?

@Mariusz Bielawski​ , I know your question is 5 months old, but in case you are someone else is searching for this - Go to Admin -> Security Settings -> Recipient Authentication Triggers.