This snippet is used on the following knowledge base article - https://kb.wpbeaverbuilder.com/article/463-customize-settings-forms

customize-settings-form.php

<?php // do not copy this line, start with line 3

function my_builder_register_settings_form( $form, $id ) {
  
  if ( 'row' == $id ) {
    // Modify the $form array for rows as needed.
  }
  elseif ( 'button' == $id ) {
    // Modify the $form array for button modules as needed.
  }
  
  return $form;
}
add_filter( 'fl_builder_register_settings_form', 'my_builder_register_settings_form', 10, 2 );