In my theme's ***function.php:***

```
//Custom Image Sizes
set_post_thumbnail_size( 150, 150, true );
add_image_size( 'kaira-slider', 1140, 500, true );
add_image_size( 'kaira-featured', 652, 375, true );
add_image_size( 'kaira-grid-post', 360, 230, true );

```

And in my ***content.php:***

```
<div class="featured-img">
        <a href="<?php the_permalink(); ?>" class="post-thumbnail">
            <?php the_post_thumbnail('kaira-featured', array('class' => 'img-responsive')); ?>
        </a>
    </div>

```

I tried to change the size from **'kaira-slider'** to **'kaira-featured'**, but the size won't change. I'm using the kaira-Theme.

How to force the theme to change the image size?