The family tree on your app is the same tree that you have on the family tree online on MyHeritage.com.
When you update on the app, it will update automatically on the site.
The Family Tree Builder that you have in your computer is a software that is locally stored in your computer. In order to update your family tree with the information that was added via app or family tree online, you have to sync, by opening the tree on Family Tree Builder and clicking on the 'Sync' button in order to sync the two platforms (online tree and Family Tree Builder tree).
i have just downloaded the latest version of the MyHeritage app onto my iPad. When ever I try to edit any details all goes fine until I hit the save button then I get "Permission Denied. Please contact site manager" as I am the site manager I can't understand what to do?