In order to templatize/parametrize an SSH connection field, click on the name of that SSH connection, click on the field to be templatized, and click on the Inject Template.
Inject Template icon located next to that field. Not all fields have this icon, because not all fields can resolve injection values. An example is highlighted below.
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When selected, the following template selection popup appears:
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Select the Data Template and field of choice and click on Inject. This will templatize the selected field.