An old SSL certificate is seen on a domain, while the new one is installed.
The certificate is not properly configured, or configuration changes are not applied.
Make sure that the new certificate is set in Hosting Settings of the domain;
In case of dedicated IP address, make sure that the new certificate was assigned to the domain's IP address and not just added to the domain's "Certificates" repository;
In case of shared IP address, make sure that Server Name Indication (SNI) is supported and activated;
Try to restart Apache:
for RedHat-based operating systems (except for CentOS 7):
# service httpd restart
for CentOS 7:
# systemctl restart httpd
for Debian-based operating systems:
# service apache2 restart