As Symbiostock itself is not a theme, but a plugin, you have the freedom of easily changing themes at anytime. If you ever decide you that you want to completely change the look of your website with a new theme, or you want to trial between different themes, you can do so without any worry as your Symbiostock plugin will not be affected; nor will it affect the process of switching themes. Your Symbiostock settings will also remain the same through theme switches.
To change your theme follow instructions found on WordPress theme support.