Kate,
This element cant directly be customised in the settings - but this has been put to the devs.
A workaround is to insert an html element after the ranking and force change the text with javascript.
- Create a text element directly after the ranking questions
- click the code button ‘</>’ in the formatting bar
- Paste the following in - updating the required text in bold below
<script>
document.currentScript.closest('.se_item').previousElementSibling.querySelector('.se_instruction').textContent='insert custom instructions'; </script>
We hope this helps