Check topic_index.html ( ow_plugins/forum/views/controllers).

{if $post.edited}
                <div class="ow_post_comment ow_ic_edit">{text key='forum+post_edited'} <a href="{$avatars[$post.edited.userId].url}">{$avatars[$post.edited.userId].title}</a> {$post.edited.editStamp} </div>
            {/if}

Please note that any changes you do in .html files will be lost if you update the software.

If you would like to change just the wording, then no need to edit .html files. Just go to admin panel>>settings>>languages >> find the phrase "The Forum post is edited by" and change it to whatever you want.

Topic was moved from General Questions.

Such an awesome post. I find this so helpful! Painters Fort Wayne