Trying to change Max Length of characters for Title and Description for all Parallax sections!

From theme-settings-design.inc I increased the maxlength from 1000 to 2000 but there is no change! Which file do I need?

$form['md_alpine_settings']['design']['design_parallax']['parallax_'.$i.'']['pr_'.$i.'_title'] = array(
'#type' => 'textfield',
'#title' => 'Parallax '.$i.' Title',
'#default_value' => theme_get_setting('pr_'.$i.'_title') ? theme_get_setting('pr_'.$i.'_title') : '',
'#max_length' => 2000,
);
$form['md_alpine_settings']['design']['design_parallax']['parallax_'.$i.'']['pr_'.$i.'_des'] = array(
'#type' => 'textfield',
'#title' => 'Parallax '.$i.' Description',
'#max_length' => 2000,
'#default_value' => theme_get_setting('pr_'.$i.'_des') ? theme_get_setting('pr_'.$i.'_des') : ''