title: Modify a Gravity Form button with PHP
body: <p>I don't find how to convert the gravity form button "previous" to another word "jump back".
  Does someone can give me a tip?</p>
  
  <p>add_filter( 'gform_previous_button_13', 'previous', 10, 2 );</p>
  
  <p>I don't find the filter to add another word instead.</p>