The "Settings" window should show up automatically in front of the bigger window with the logo, when you start up ProjectCoordinator Desktop. Most likely has something happened with your computer. In most cases a restart will solve the problem. If not, you can always click on the button "Settings" to show the window. If your Settings window goes blank/white you can try to click on the X and close it. After that you can click again on the button "Settings" in the big window. Then it should be normal again.
In PC you just click on the button "Settings" in the big window.
In Mac you have to right-click on the ProjectCoordinator Desktop-icon at the bottom (or side) in the Dock. Then you see a contextual menu of additional choices where you can find "Settings" and left-click on it to show the window again.