charles99
You can try this way to override:
1 - Copy this file: \plugins\system\t4\themes\base\html\layouts\t4\layout\offcanvas.php
2 - Paste into template folder:
\templates\t4_blank\html\layouts\t4\layout
Note that this 'layout' folder may not exist, you can create it.
3 - Open the new file: \templates\t4_blank\html\layouts\t4\layout \offcanvas.php
then change the JText T4_OFF_CANVAS_TITLE as you wish.
<h3><?php echo JText::_('T4_OFF_CANVAS_TITLE') ?></h3>
If your site is multilingual site, it's better to add translation for this 'T4_OFF_CANVAS_TITLE' language constant. To do this, go to Admin panel of your site > Extensions > Languages > Overrides and add translation for it.
Regards