wpForo theme files contain the markup and template structure for frontend of your forum. Theme files can be found within the /wpforo/wpf-themes/ directory, in current active theme folder, for example /classic/. You can edit these files in an upgrade-safe way using overrides. For example, copy the certain or all files of /classic/ folder into a folder within your current active WordPress theme named /wpforo/, keeping the same file structure.
Example: To override the “Topic List” template file of the Extended (#1) forum layout, copy:
wp-content/plugins/wpforo/wpf-themes/classic/layouts/1/topic.php
to
wp-content/themes/yourtheme/wpforo/layouts/1/topic.php
The copied file will now automatically override the wpForo default theme file. All changes in this file will not be lost on forum update.
IMPORTANT: Do not edit these files within the core plugin itself as they are overwritten during the upgrade process and any customizations will be lost.