Option to automatically lock survey in landscape orientation for cell phones?

As fast as I know, there isn’t a native way in Qualtrics to automatically lock the survey in landscape orientation on mobile devices. Most mobile browsers (especially on iOS and Android) don’t allow web pages to force orientation, due to user experience and security policies.

However, a common workaround is to use custom JavaScript to detect the screen orientation and show a message asking the user to rotate their device. Here’s a basic version you can add to your survey (either under Look & Feel → Add Custom JS, or within a question’s JavaScript):
Qualtrics.SurveyEngine.addOnload(function () {
  function checkOrientation() {
    if (window.innerHeight > window.innerWidth) {
      // If in portrait, replace content with prompt
      document.body.innerHTML = "<div style='text-align:center; margin-top:30vh; font-size:1.5em;'>Please rotate your phone to landscape mode to continue.</div>";
    }
  }
  checkOrientation();
  window.addEventListener("resize", checkOrientation);
});

Hope this helps!
-- Rochak

@Nadia,

In my opinion, a better way to handle this is with a CSS media rule.  See this.