How can the Apple 4 screen not be horizontal? When you send a text message, it becomes a bar. Where is the setting?

Apple 4 has the function of locking the screen rotation. As long as the screen phone is locked, it will not become a horizontal version.

Setup steps:

In Apple's home screen (desktop), slide the screen from bottom to top with a single mobile phone, and a new toolbar will appear at the bottom of the screen;

The fifth tool in the first line of the toolbar is the screen rotation lock. Click it to lock the screen.