Showing Help Center article time in 12-hour format

By default, Help Center article timestamps appears in 24-hour format.  If you want to display timestamps in 12-hour format, as shown below, you can do so by modifying your Help Center theme's HTML and CSS. 

To display time in 12-hour format

In the Help Center, click
Customize design
in the tools panel on the lower-right side of the page. 

Great question!  The timezone settings within the interface is meant for internal agents and showing the time of updates within tickets.  I'm not aware of a plan to push that setting out to Help Centers as well, so for now it will remain a custom JavaScript solution. 

Any time you go into an article, make a change, and then update the article, it should update the time.  If you weren't seeing it right away, it was probably because the browser cache hadn't refreshed yet.  Doing a hard refresh on your browser will usually take care of this.