Following are the steps on how to upgrade PhpMyAdmin to 4.0.5 on Centos 6.x / Apache

1. Login to Webmin, select 'Others' from the menu on the left, then select 'Command Shell'. Alternatively use Putty to execute below commands from shell.
2. Install Required Repositories for PhpMyAdmin 4.0.5:

If using CentOS 6.x - 32 Bit OS, execute following commands in command shell (one by one):

rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
rpm -Uvh http://dl.fedoraproject.org/pub/epel/5/i386/epel-release-5-4.noarch.rpm
rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-5.rpm

If using CentOS 6.x - 64 Bit OS, execute following commands in command shell (one by one):

rpm -Uvh http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
rpm -Uvh http://dl.fedoraproject.org/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm
rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-5.rpm

3. Execute following command in command shell: ```

yum --enablerepo=remi install phpmyadmin -y

4. Restart Apache

Note: If you're planning to do this through Putty or other SSH connection, just run the same sequence of commands (above).

Login to PHPMYADMIN, your PhpMyAdmin should now be upgraded to PhpMyAdmin version: 4.0.5.