How to customize the text of "SUBMITTED BY" (article)
In node.html.twig change the line SUBMITTED BY to WRITTEN BY

  {% if display_submitted %}
    &lt;footer class="node__meta"&gt;
      {{ author_picture }}
      &lt;div{{ author_attributes.addClass('node__submitted') }}&gt;
        {% trans %}Submitted by {{ author_name }} on {{ date }}{% endtrans %}
        {{ metadata }}
      &lt;/div&gt;
    &lt;/footer&gt;
  {% endif %}