Hi Mary,
You can try a solution that we use.
Paste the code below in a custom html element in a marketo landing page.
Also replace the code where
PUT THE URL PATH OF YOUR IMAGE HEREappears with the url path of your jpg image.
<style>
button[type="submit"].mktoButton{
display:none !important;
}
</style>
<!-- jquery if needed OPTIONAL -->
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
setTimeout(function(){
$('button.mktoButton[type=submit]').after('<img src="PUT THE URL PATH OF YOUR IMAGE HERE" style="cursor:pointer" class="myOwnButton"/>');
$('img.myOwnButton').click(function(){
$('button.mktoButton[type=submit]').click();
});
},2000)
});
</script>