Screen does not work with PS4?

I've connected my Ps4 with the monitor and get this message permanently (see picture) what can I do now?

Put down the resolution of the PS4 (for example, 1280x720)

Is it already in the message. Switch the mode

Where do I do that? I do not know about the Ps4 at all

When starting the console, hold down the power button.
Wait until the console makes a second beep.
The console now starts in "Safe Mode"…
Choose the option "Change Resolution" here.
In the new menu you can change the PS4 resolution.

Ok, nothing changes anyway

The moment you write that, you had a picture.

Yes, if i go to resolution then it's gone again

Maybe you should change the resolution on a FullHD screen.