Change the Value of h1 Element within a Form with JavaScript

Try:

document.getElementById("yourH1_element_Id").innerHTML = "yourTextHere";

You can use this: document.getElementById('h1_id').innerHTML = 'the new text';

document.getElementById("myh1id").innerHTML = "my text"

You may try the following:

document.getElementById("your_h1_id").innerHTML = "your new text here"