WP_Query displaying ALL posts

I cannot figure out why my WP_Query always displays all my published posts regardless of what I put in the arguments.

<?php 

    $args = array('numberposts' => 1,
                    'meta_key' => 'display',
                    'meta_value' => 'about'
    );

    $about_preview_query = new WP_Query($args);

    if ($about_preview_query->have_posts()) {
        print "<h1>FOUND POSTS</h1>";
    }

    while ($about_preview_query->have_posts()) {
        $about_preview_query->the_post();
        print "<h1>";
        the_title();

        print "</h1>";

    }
?>

Am I doing something wrong here? After readings the docs on WP_Query() I cannot figure out where I’m going wrong, appreciate any help I can get.

Update

I’ve tried this code and I am still getting the same response. All the posts are being returned in the loop.

    $args = array(
        'posts_per_page' => 1,
        'meta_query' => array(
            array(
                'key' => 'display',
                'value' => 'about',
                'compare' => '=',
             )
        ),
    );

Update 2

It seems if I print $about_preview_query->found_posts the output is 1. So I suspect there is something wrong with how I am looping the posts:

<?php if ($about_preview_query->have_posts()): ?>

    <h1>Has <?php print $about_preview_query->found_posts ?> Posts</h1>

    <?php while ($about_preview_query->have_posts()): $about_preview_query->the_post(); ?>
        <h2><?php the_title(); ?></h2>
    <?php endwhile; ?>

<?php endif; ?>

It is because you are giving wrong arguments. Provide right arguments to WP_Query().

Also have a look at the custom field parameters

One more thing, you will have to use code like

$args = array(
    'posts_per_page' => 5,
    'meta_query' => array(
        array(
            'key'     => 'display',
            'value'   => 'about',
            'compare' => '=', // (Read all comparison operators at provided link)
        ),
    ),
);