Adjusting forum/activity page?
Using Jamroom
The URL for that page has some html stuff in it, it looks a bit strange. (screenshot)
The same url without that stuff works too, its:
https://fotmd.com/forum/activity/250/dusty-turtle/p=15
It should be the jrAction_item_index.tpl file that controls that page, it doesn't seem like it is on your site though.
The list should be being generated by a call like this:
{jrCore_list module="jrAction" profile_id=$_profile_id order_by="_item_id numerical_desc" pagebreak="12" page="1" pager=true}
and the solution to limiting is to change 'pagebreak' to 'simplepagebreak' then add 'limt=100':
{jrCore_list ........... simplepagebreak="12" page="1" pager=true limit=100}
In order to figure out which template you need to adjust you can turn on "Template names in source" from:
ACP -> MODULES -> DEVELOPER -> DEVELOPER TOOLS -> GLOBAL CONFIG -> TEMPLATE NAME IN SOURCE
That will show up in the source code to the page. This should be done at a quiet time of day for the site.
I tried to adjust the jrAction_item_index.tpl on your skin but its not that template. First step is to figure out which template controls that page.