@Tracy Anytime you are uploading an Image using the standard WordPress header uploader, you need to make sure the image that you’re uploading matches the exact size of the image size in your functions.php file. So check in your functions file for this –
//* Add support for custom header
add_theme_support( 'custom-header', array(
'width' => 360,
'height' => 164,
'header-selector' => '.site-title a',
'header-text' => false,
) );
Find out the exact size of your image, and then change the functions.php code to match that size….then it should upload perfectly without having to crop. That’s the way the standard WordPress uploader works.