Depending on which region you are, you either press circle (O) or X to enter/confirm and the other is for back on the PS4. If you buy a console in Asia, then system-wide circle is confirm.
(Though we wish Playstation addresses the issue that some games still use the X to confirm but that’s another topic.)
The latest firmware, version 6.50, now lets you switch the two buttons primary function. So if you prefer X to confirm like how it is in regions outside of Japan and Asia, now you can.
This feature only applies to certain regions, and we can confirm at least for Malaysia, it is available.
Go find the setting under Settings, then Systems.
The update also adds Remote Play support for iOS. Regions that support NicoNico streaming also get to stream at 720p.