changing the header image size from 350×350

i am trying to change the size of the header image in stitch.
url: https://www.aboriginalculturlatraining.com.au

on the home page the logo is rather large and makes menu’s fall off the page. i have tried chnaging the size of the file i have loaded and i have also tried changing the code here
function stitch_custom_header_setup() {
$args = array(
‘default-image’ => ”,
‘default-text-color’ => ‘fff’,
‘width’ => 350,
‘height’ => 350,
‘flex-height’ => true,
‘wp-head-callback’ => ‘stitch_header_style’,
‘admin-head-callback’ => ‘stitch_admin_header_style’,
‘admin-preview-callback’ => ‘stitch_admin_header_image’,

with no luck. where and what else can i try.