Annoying Facebook Display Issue

Hello,

When using the Facebook App on my Samsung Galaxy Tab4, Facebook news feed displays as portrait on a landscape background, with blank grey space either side of the news feed. If I uninstall the app and re-install (or clear the cache), the display reverts to landscape until the tablet is put to sleep or powered off. Then on re-start, display is back to portrait. It seems like a small complaint but there is probably an easy fix, which I would appreciate some guidance on! Cheers