Why doesn't my cell phone switch itself off?

I have a Huawei Mate 10 Lite and it usually turns off when you don't touch the cell phone for 30 seconds. You can set that too. But now if I don't type in my cell phone for 30 seconds, pictures come up. Why? Can you change that?

This is called a screen saver. Can you change in the settings.

Thank you

I already know the answer

With pleasure ;-)