Lock the questionnaire with username and Password

I hope to get the way to lock the questionnaire to prevent anyone to see and enter the data into the questionnaire, I need just the ones who can I give them username and password for each data entrant.

None can see the questionnaire even he/she has the link of the questionnaire.

Have you gone through our support articles Managing Permissions and Row-Level Permissions? If your request is something different from these, could you explain how?