Identify who login and submit form with pre-fill and hide content problem

I have a project to make job evaluation performance system by

  • use Web app for login feature by coding in GAS in google sheet.
  • get user and password to match in UserCredentials sheet in google sheet
  • if user and password match case then open form that match case with pre-fill username in the first question and blind it and show other question for fill up by user

problem is I found out many ways to active pre-fill and hide first question , but it’s not work till the end. I’d like to use process auto detect entry ID from first question insteed direct fill-up in sheet bacause of there’re so many form in project.(BTW even direct fill-up Entry ID also not work in pre-fill function)

so could you please advise to me how to process the next step to complete this project?

  • Sample Code and materials

https://docs.google.com/document/d/1EaUVucNPBfj5UaALQoeFJF5BuxMtF9EwMG4mMCW5-Sw/edit?usp=sharing

so could you please advise to me how to process the next step to complete this project?