@Ronald-Dupas ,
You haven’t defined your chosen browser that you want to use, so minus that information, very little factual help can be provided. However, if you are wanting to use the Firefox Browser, the below pic will show you want you’re looking for there, by clicking Settings->Applications and choose the file type you want opened by default by the Notepad++ application, click the right menu selection, and then select Use other... and browse to your chosen application.
BrowserDefaultTextEditor.PNG