Two questions

I have an rp site, and I use the main rp as a sticky so it;s easy for everyone to find. This morning when I went to check it, the forum had split itself.
Pictured here

As you can see, there are two of the same forum. One is a sticky, and one is not. I was wondering why it split itself, and where in the admin panel I can go to fix it.

I appreciate any help with this.

So after some heavy searching, I found the 'forumotion limitations' topic which stated that once a topic hits 990 post, it locks and splits.
Now, also on the topic of posts and posting, I was wondering if there was a way to display more then 5 previous posts below when replying to a topic.

Ok, so I had fixed it. I split the all the posts from one forum and merged them to the other
well guess what?
It split itself again, and all the work I did of splitting and merging was completely undone.

So, obviously it's not just a sticky thing. Where do I go to edit the limit of posts in a topic? I can't find the option in my admin panel anywhere

ACP >> General >> Messages and Emails >> Configuration >> Posts Per Page >> Set it to whatever amount of posts you want per page.

That's not the problem though. It's not how many post per page, it's the limit of pages per topic.
Though thank you for reminding me where that option was. I keep forgetting that the 'messaging and emails' section is for all messages and not just 'pms' and such xD

Also, in regards to posting, where can I change how many posts are displayed when you're replying?