CODE EXAMPLE FOR PHP

learndash logo link

//CHANGE LEARNDASH LOGO LINK 
add_filter( 'learndash_focus_header_logo_url', function( $header_logo_url = '', $course_id = 0, $user_id = 0 ) {
	$header_logo_url = 'CUSTOM_URL';
	return $header_logo_url;
}, 30, 3 );