Hi @Jiriskap, let me see if I can help out here.
Are you referring to the navigation bar at the bottom of the screen? Hiding the navigation bar, also known as fullscreen mode cannot be controlled by the UI settings of the device. Fullscreen mode can be enabled in the app code of some apps such as Youtube, Netflix and various gaming apps. Depending on the app or content, the proper fullscreen mode will be activated automatically.
There are, however, third-party apps available on Google Play that will offer fullscreen mode for all apps and content, keep in mind though that Sony does not warrant or guarantee the performance of any third-party applications
I hope that answered your question, please get back to me if I have misinterpreted your post.
