When you add upgrade/implementation steps you get prompted for “Version”, and that is a comma-separated list of versions that this implementation can upgrade from. It is always to the current version.
You can use the configuration parameters to create new parameters. This is for parameters that are part of the current version but were not part of the version(s) you list in “Version”.
The implementation part of the upgrade follows the same syntax and setup of the main Implementation, but if tables were already created in older versions of the job, they are typically omitted in the upgrade implementation.