By editing the API Template definition, you can change the synapse configuration of all APIs that are created. To edit the template, navigate to <APIM_HOME>/repository/resources/api_templates directory in your local API Manager setup and change the necessary template XML file. For example, to change the resource content of APIs, edit api_templates_resource.xml file. This changes the resource definition of all created APIs.
If you are using a distributed API Manager setup (i.e., Publisher, Store, Gateway and Key Manager components are running on separate JVMs), edit the template on the Publisher node.