When you Complete a Master Action, all the Sub-Actions are listed for you to complete in the same process:
Things to be aware of:
Changing the Completion Date for a Master Action will also set the Completion Date for any Sub-Actions have yet to be Completed.
Ticking the Completed checkbox on the Master Action, will also tick it on all Sub-Actions that have yet to be Completed.
Refer to Actions and How To Complete An Action for more information about Actions.