Usually making changes to a category tree should result in an immediate update on the front-end. However, if this is the first time you are working on your category tree, or if you are working on a new category structure that has to replace the existing one, there is one additional step to take.

Go to the Magento Backend > Stores > All Stores. In this list, you can set the root category per store. So, if you want to use a different category tree per store, that is also something you manage in the following screens.

Select the store for which you want to change the root category in the 2nd column. 

Now, select the new Root Category which you have created in Business Central, and click Save Store.