Default Value ('std') of a Radio Field

Hi we have several blogs that contain existing blocks built with MB Blocks. I am looking to add a radio button with a default value of Yes. The code below works on any new block that is added to a post/page but is there a way to force the default on blocks that already exist throughout the site?

[
                'name'    => __( 'Editor Comment?', 'bestxy-box' ),
                'id'      => $prefix . 'editComment',
                'type'    => 'radio',
                'options' => [
                    'Yes' => esc_html__( 'Yes', 'bestxy-box' ),
                    'No'  => esc_html__( 'No', 'bestxy-box' ),
                ],
                'std'     => 'Yes',
                'columns' => 6,
                'inline'  => false,
            ],