<button onclick="changeAndStoreText()">Change and store</button>
<p id="text">Text</p>
<script>
function changeAndStoreText(){
    localStorage.setItem('firstScreenText', document.getElementById('text').textContent)
    document.getElementById('text').innerHTML = 'Another text';
    window.onload = function () {
    if (localStorage.getItem('firstScreenText')) document.getElementById('text').innerHTML = localStorage.getItem('firstScreenText');
    }
</script>