Until now, the only solution to edit the modification date of an
article in Joomla, is to go through the database. This technique is
reserved for people with the access rights and skills to do so.
Modify Date plugin has been specially designed to
allow you to modify this field directly from the Joomla
administration panel, without having to open in the database. Thus,
you have complete control over your site and how your articles are
displayed, specialy in lists. As this plugin is free, you have
every reason to install and use Modify Date right
now!
Read more https://extensions.joomla.org/browse/new/extension/news-display/articles-display/modify-date