Having articles in the correct order and easy to find position for a customer, is a key success factor of your Help Center. In KnowledgeBase it's easier than you think, you just need to drag chosen topic/article and drop it in the place you would like to be! 

Here, you have step by step how o do it ;)

All changes will be visible both in Help Center and Livechat's Agent's App after 1 minute!