According to official information, this process has been simplified in the latest version of the product. If you can't complete the process by yourself using the current version, I strongly suggest that you upgrade your program to the latest version. To do this, just visit the official website to obtain a download link.
After you installed the latest version, open your project, and go under Parametric Surface tab > Start Parametric Surfacing icon. Your project will be automatically converted to a parametric model.