how to change resolution of my game in unity 5?

I am a beginner and i started the space shooter project.
in the 2nd video the guy who is speaking changed the resolution in player settings to (600900)
in unity 5 there are 2 slots for default width and height ,i changed them both to (600
900) but
in the game view in the upper left it says "using resolution (306*459) so i want to know if the 2 slots are for changing the resolution and if not then what do!

Player settings only defines what the build will look like. The dropdown on the top left of the Game view in the editor is only in the editor. So when you set it to something larger than what fits into the Unity application, it will tell you “using…”, but when you build, it will use whatever you specified. So for WebPlayer you can type in default screen size in Player Settings, and mobile will use whatever the device the build is running on has.