Hello,
In case, I want to change SSL to a new domain and I don't want to use it on old domain, it is possible?
And do I need a new SSL certificate if I change my domain name?
Depends on what SSL certificate you purchased. Some will allow re-issuing for a different domain, but most are locked to the domain you purchased, meaning you will need to purchase a separate one.
1. Create a New CSR for the new domain name.
2. Certificate authority will provide your SSL certificate files and key file,.
3. Install this certificate on your server.
The answer to your question is yes you will need a new SSL certificate. You can contact your SSL provider and ask if they will reissue the certificate with a new CSR.