I would like to have more than five items in the "Recent Topics" list, but I can't seem to find where to change that, if possible at all.
You can set a maximum of 50 in Modify Profile > Look and Layout
but there is a time limit to what is considered a "recent" topic (not sure if it is set by hours or restart of day; an Administrator would know more).
If only five topics have posts within the "recent" time period then that's all you will see.
You can set a maximum of 50 in Modify Profile > Look and Layout
That is per page when you navigate the forum. I take it that the question concerns not that, but the five "Recent Topics" on the HA front page.
Which has a time limit as to what is considered to be "recent".
Edit: But you're probably correct. The setting doesn't change the number of posts on https://hydrogenaud.io/index.php/board,28.0.html so it probably won't change how the front page is displayed either.
I had already set those to 50 before starting the thread.
The thing is that there were more items in the front page list before, but now it's only five.
As
@korth says, it shows only recent threads. So, if there are only 5 threads to which has been posted the last 3 days (or something like that, I'm not sure), then it will shown only 5 threads. If there are only 3, it will show those 3.
It happens to this site sometimes, Very few new Topics, then a new post comes along sometimes from a troll, gets things alive & kicking again.