If you need to switch between applications, I found I did best with one screen set up to be an extension of the first. Your laptop will have a dual display setting. When you first connected the desktop display, your computer likely asked you if you wanted it to be a duplicate display or an extension. If it is an extended display, you can choose which display is the primary.

By having an extended display, you can look back and forth between screens rather than having to remember between them as you click between applications. This reduction in memory stress can make a big difference.

You can also drag and drop between the two displays.