I've uploaded crt and key files via admin->security->certificate
But I check the current certificate on the site and it is still the old ones.
Am I missing something ?
When updating SSL certificate via web interface, it will be applied to a new connections. So you should renew the page in browser and maybe should clean browser data to display a new SSL certificate.
WCS should be restarted to apply a new certificate when updating it via command line using keytool.
Anyway, all the connections are dropped while WCS is restarting, so it is a suitable solution too.