I think you want to change the default file format for new documents that Notepad++ uses when you run the program from the icon. If that's correct. You can change the File format of a new document like this.
Navigate to C:\Program Files (x86)\Notepad++
Then open the file config.model.xml (if you use Notepad++ to edit you won't be able to save as the file is in use.)
Look for this line around line #28
<GUIConfig name="NewDocDefaultSettings" format="0" encoding="0" lang="1" />
Then you have to change the value for "lang=0" by default it opens everything in txt format. If you look at step 3 I have "1" because I use it for PHP. You'll have to check the source code if you want to change it to anything else. As the developers did not list all the languages in this configuration file you could use.
Best Answer
You can disable the list of recent documents by changing your Recent Files History settings under
While there is no an explicit "disable" feature, you can set the "Max. number of entries" to 0.
(I'm currently using Notepad++ v6.8.3)