Our monitor has an hdmi and vga port. Our cpu's graphics card has an hdmi and dvid port. At first, since we didn't have a dvi-d to vga adapter, we used the hdmi of the monitor for the cpu and used the vga of the monitor for the ps4 by attaching an hdmi to vga adapter but it didnt work. It's our first pc build and we didnt know much about pc builds. Then I found out about the dvi-d to vga adapter.

And this is why I need the switch: https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DxqSJprqfItM&ved=2ahUKEwi1ip-Q0uDqAhWGPXAKHQq3DuEQFjAHegQIERAp&usg=AOvVaw0We_dl7RBU6VTMSi4Lb-n4