You can do this but you have to hack the theme (not the child theme) so be careful and don’t blame me if it all goes wrong!
Go to wp-content/themes/custom-community/core/includes/theme-generator and open theme-generator.php. You can then change the contents of the div. Scroll to line 434 and replace the content of the credit div with whatever you like. In my case I have put
'<div class="credits"><?php printf( __( ' - Design by Fandam Studios | Development by MazuriDesign. ', 'cc' ), bloginfo('name') ); ?></div>'
Obviously if you update the theme in the future you will need to redo this as it will be lost.