When you edit a Template from the Templates section, the update is applied immediately to any Flow step that uses that Template. This includes people who are already due on the step. Once the Flow refreshes, the Action will automatically display and use the latest version of the Template.
Templates are not locked at the time a person becomes due on a step. This means you do not need to remove or re-add people to the Flow, or make any additional changes for the update to take effect. Anyone who is already due, as well as anyone who enters the step after the update, will use the same updated Template.
This behavior ensures consistency across your Flow and makes it easy to refine messaging, fix errors, or make last-minute adjustments without disrupting active steps.