Eventually I got it right, this is the coed I worked on and placed it in the head of the form:
<script>
jq(document).ready(function(){
jq(window).load(function(){
//alert("Page loaded.");
//Hide urgency and impact on page load (so for all status changes it will remain hidden on edit mode)
jq('select[name="SET.urgency"]').hide();
jq('select[name="SET.impact"]').hide();
});
});
</script>