If you want to modify or simply check the contents of a module, you can extract it.
The extract operation opens a copy of the tasks contained in the model in a new flow.
If you want to overwrite the source module, in order to propagate the changes to all flows that use the module, you must export the module by clicking Export Process in the toolbar, browse to the original file, select it and click Save, confirming you want to overwrite the original file.
As modules are often extracted for debug purposes, if the module contains computed data the data source is included in the extracted module, even if your module is an Execute Rulex Process File task. This obviously facilitates debug operations, but remember to delete the source task if you decide to overwrite the original module.
Right-click the module (Execute Rulex Process File or Rulex Process File Source task) and select Extract Module.