quickly insert data from google forms into sheets

You cracked the difficult steps 1 and 2. The Step 3 is easy.

function autoFillCaseInfofromIntake(e) {
  var Timestamp = e.values[0];
  var Source = e.values[1];
  var FullName = e.values[2];
  
  var templatefile = DriveApp.getFileById("I inserted ID here");

  var templatepopulatedfolder = DriveApp.getFolderById("I inserted ID here");
  
  var copy = templatefile.makeCopy(FullName, templatepopulatedfolder);
  
  var newsheet = SpreadsheetApp.openById(copy.getId());
  var sht1 = newsheet.getSheetByName("Sheet1");//open the default sheet 1 or if you want you can rename the sheet or create a new sheet
  sht1.getRange("A1").setValue(Source); //populate any cell with value captured by the form
  sht1.getRange("B1").setValue(FullName);

}

Explanation:

• Get the desired sheet with getSheetByName(name).
• Get the cells you want to change with getRange.
• Set the values of the cells with setValue(value).

I’m sure you figured out how to run the above script “On formSubmit”