Issue: you need to manually specify a new certificate in IIS
Background: by default IIS picks the certificate it think is best, in some cases this could lead it to choosing an old cert or a self signed cert rather than the cert you would prefer)
Manually specify your preferred SSL certificate for the Default Website or whichever IIS Website you would like to assign your certificate.
1) Open IIS Manager, expand the web server, expand sites
2) Right click Default Website or the website in question and click “Edit Bindings…”
3) Next select port 443 in the bindings list, or any other ports using SSL
4) Click the SSL certificate dropdown to select the desired certificate (you can click ‘View’ to verify the properties of the cert are what you expect)