Can’t update value in multi dimensional array

I have an array as below. I wish to update the value of [form_id] => 79 to [form_id] => 123.

Array
(
    [directory_table-columns] => Array
        (
            [6433fed3e408d] => Array
                (
                    [id] => 20
                    [label] => Rank
                    [form_id] => 79
                )
            [6433ffa1bf847] => Array
                (
                    [content] => <a href="{site_url}/user/{Player:1}">{Player:1}</a>
                    [label] => Custom Content
                    [form_id] => 79
                )
...
...

Below is my code.

foreach ( $src_gravityview_directory_fields as $key1 => $value1 ) {
        foreach ( $value1 as $key2 => &$value2 ) {
            $value2['form_id'] = $dest_form_id;
        }           
}

But the value of form_id doesn’t change. I also tried the below but no joy.

foreach ( $src_gravityview_directory_fields as $key1 => $value1 ) {

    foreach ( $value1 as $key2 => $value2 ) {
        
        $value2[$key2]['form_id'] = $dest_form_id;
    }           

}

I tried this but it caused an infinite loop.