using the counter and loop

Hi
Not sure if this is the right thread soory if not.
I am using the accessmag theme which shows 2 large posts side by side and then smaller posts underneath. I would like it to show 1 large posts and then smaller posts underneath but I sm struggling to change the loop with the counter.

<div class="first-block-wrapper">

                    <h3 class="block-cat-name"> 

                        <span><?php echo esc_attr( $category_info->name ) ; ?></span>

                    </h3>

                    <div class="block-post-wrapper clearfix">

                    <?php                                

                        $block1_args = array(

                                            'category_name' => $block1_cat,

                                            'post_status' => 'publish',

                                            'posts_per_page' => $posts_for_block1,

                                            'order' => 'DESC'

                                            );

                        $block1_query = new WP_Query( $block1_args );

                        $b_counter = 0;

                        $total_posts_block1 = $block1_query->found_posts;

                        if( $block1_query->have_posts() ) {

                            while( $block1_query->have_posts() ) {

                                $b_counter++;

                                $block1_query->the_post();

                                $b1_image_id = get_post_thumbnail_id();

                                $b1_big_image_path = wp_get_attachment_image_src( $b1_image_id, 'accesspress-mag-block-big-thumb', true );

                                $b1_small_image_path = wp_get_attachment_image_src( $b1_image_id, 'accesspress-mag-block-small-thumb', true );

                                $b1_image_alt = get_post_meta( $b1_image_id, '_wp_attachment_image_alt', true );

                    ?>

                        <?php if( $b_counter == 1 ){ echo '<div class="toppost-wrapper">'; } if( $b_counter > 2 && $b_counter == 3 ){ echo '<div class="bottompost-wrapper">'; }?>

                        <div class="single_post clearfix <?php if( $b_counter <= 2 ){ echo 'top-post non-zoomin'; }?>">

                            <?php if( has_post_thumbnail() ) { ?>   

                                <div class="post-image"><a href="<?php the_permalink();?>"><img src="<?php if( $b_counter <= 2 ){echo esc_url( $b1_big_image_path[0] );}else{ echo esc_url( $b1_small_image_path[0] ) ;}?>" alt="<?php echo esc_attr($b1_image_alt);?>" /></a>

                                    <?php if( $b_counter <= 2 ) { ?> <a class="big-image-overlay" href="<?php the_permalink();?>"><i class="fa fa-external-link"></i></a><?php } ?>

                                </div><!--. post-image-->

                            <?php } ?>

                                <div class="post-desc-wrapper">

                                    <h3 class="post-title"><a href="<?php the_permalink();?>"><?php the_title();?></a></h3>

                                    <div class="block-poston"><?php do_action('accesspress_mag_home_posted_on');?></div>

                                </div><!-- .post-desc-wrapper -->

                                <?php if( $b_counter <= 2 ) { ?><div class="post-content"><?php echo '<p>'. accesspress_mag_word_count( get_the_content(), 25 ) .'</p>' ;?></div><?php } ?>

                        </div><!-- .single_post -->

                        <?php 

                            if( $b_counter %2 == 0 ){ echo '<div class="clearfix"></div>'; }

                            if( $b_counter > 2 && $b_counter == $total_posts_block1 ){ echo '</div>'; }

                            if( $b_counter ==2 ){ echo '</div>'; }

                        ?>

                    <?php

                            }

                        }//endif wp_query

                    ?>

                    </div><!-- .block-post-wrapper -->

                </div><!-- .first-block-wrapper -->

If any body could help that would be fantastic