Something is wrong with the rendering in the scene view,Something is wrong with the viewing in the scene view

In every scene, something happened, the view changed to something that looks like an isometric sketch, how do I fix this?

It is on Mac, using version 2018.4.14f1 Personal, with a tutorial template

Well if you check the top right of your scene view right below the axis gizmo you see that you have switched your view into isometric view mode. Just click those parallel lines again to switch back to a perspective view. The same happens when you just click the center cube of the gizmo. This can all be read in the manual