I've been told to move a site from HTTP to HTTPS. After the hosting said that they installed the SSL certificate, I thought all I had to do was to simply change the site URL from HTTP to HTTPS, but then the site is not accessible. Do I also have to change the Wordpress URL? I'm wary of doing so as it cause a site to be completely unaccessible as this changes values in the database I suppose. Should changing the site URL from HTTP to HTTPS all the necessary? If that doesn't work, it means the SSL certificate is not installed properly?