If you are someone who use multiple monitor with your computer and wondering how to record a different screen/monitor, this guide will be helpful for you.
As you can see from the above image, it is very easy. You just need to select the desired screen from "Select screen" dropdown. Also your selection will be autosaved for next time so that you don't have to select every time.
For Mac:
Unlike Windows and Linux, Mac's menubar is visible in each screen. This give another way to switch screen for Mac users. You just need to click on NeetoRecord icon in the menubar on the screen you wish to record, that screen will be automatically selected for recording.
Troubleshooting
If for some reason your connected screens doesn't appear in the dropdown, unplug and plug back in the missing screen should fix the issue. If the issue persist please try to contact support.