I want to change my primary domain name. Will this affect my current Joomla installation?
Yes, a change in your primary domain name will require your Joomla to be reconfigured.
For this purpose please use cPanel's File Manager and navigate to your Joomla's root folder. Then open the file configuration.php and find a directive similar to this:
$mosConfig_live_site = 'http://your-new-domain.com';
Please substitute "your-new-domain.com" with your new domain name and save the file.