I hope you are well today and thank you for your question.
We have created feature request in the following topic to implement this option in the future version of theme.
In the meanwhile if you want to achieve this without using child theme then you can achieve it by editing following line of code wherever you find it in the theme file /gillion/inc/helpers_blog.php
<?php echo human_time_diff( get_the_time('U'), current_time('timestamp') ) . ' ' . esc_html__( 'ago', 'gillion' ); ?>