Log onto your Plesk account.
On your Dashboard, click on 'Wordpress' on the left-hand side of the webpage.
On the information of the site you want to secure, check the 'Security status' underneath the view of the site. If you do have a security issue on your site that you need to resolve, it will display the status in red as 'Danger'. Click on 'View' to see the specific issue to be resolved.
Select the issues you want resolved and click 'Secure' in the top left of the webpage.