I am very new to google forms and it's great, but I just cannot believe there is no way to hide the back button or to limit entries to one per IP. It seems so obvious that survey or quiz creators would want these features. Surveymonkey wants to charge me $480/year for them, and I don't see a single add-on that provides them either (and if they did they would also want $100/year). Frankly given all the time I've spent trying to figure out how to do this I should have just been creating my own form, but I digress.

Anyway, is there really no way to do this using an app script? Something like

function onOpen() {
 var xpath = "//a[text()='Back']";
  var matchingElement = document.evaluate(xpath, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
  matchingElement.style.display = 'none';
}

this returns error document is not defined.

function onOpen() {
  var ui = FormApp.getUi(); // Same variations.
  var xpath = "//a[text()='Back']";
  var matchingElement = ui.evaluate(xpath, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
  matchingElement.style.display = 'none';
}

This gives error Cannot call FormApp.getUi() from this context.

It looks like the script is for the creation page not the view/user page?

Any pointers much appreciated!