The tool bar allows for quick access to certain menu commands (including those of plugins if they are registered, see Plugins). If the screen is smaller than the toolbar width, then some of its buttons will be hidden. You can access these buttons by clicking on the chevron (the double arrows) on the right of the toolbar, a menu will pop up showing you the hidden commands. You can customize the toolbar to use different icons. Notepad++ supports three modes:
To choose which mode to use, see Preferences.
To
load custom images for your toolbar, you need a special configuration
file and the custom images. To learn how to use these, please see the
following link for information:
https://apps.sourceforge.net/mediawiki/notepad-plus/index.php?title=Toolbar_Customisation