On a computer, the default width of an app is 768 pixels wide. This is used to simulate a tablet device. If you want your apps to be able to use the full-screen width of the device on a computer, you can go to the builder screen and click on the Layout Settings button and then select the settings and specify what the max width should be. 1024 px will provide an improved viewing experience on a PC and 1900px works well for App intended to be viewed full screen on a computer.
If the max width is larger than your logo width, it may cause it to pixelate.