Notepad++ custom syntax highlighting setting – where to look for it

When you open a file in notepad++ it will attempt to load syntax highlighting for the contents based on file extension.

If you use custom extension for one of the existing languages you can add the custom extension in Settings -> Styler Configurator. Select language and add the extension in "User extension" edit box. To add multiple extensions separate them using Space.

You then need to re-open your file to see the syntax highlighting applied.

You can also change syntax highlighting style by selecting a different language from language menu.

The only work around I know of is to click on Language from the context menu and select the last option User-Defined (assuming it's not in use). This will remove all highlighting. Then, to put it back on, you can select the language again. All of this is with the mouse though.

To use the keyboard, the 'shortcut' would be alt + L + U (so, not really a shortcut). Then, to put the language back you'd have to do the same but for your language. For example alt + L + H + HEnter would reset it to HTML