A simple example to show the preferred way to change Momtaz current layout.

functions.php

<?php

add_action( 'after_setup_theme', 'sample_after_setup_theme', 11 );

/**
 * An action for 'after_setup_theme' hook.
 *
 * @return void
 * @since 0.1
 */
function sample_after_setup_theme() {
	Momtaz_Layouts::set_current_layout( '1c-fixed' );
}