If you wish to change something in already enabled automation, you may start right away, without disabling the sequence.
To access the editor, you should proceed to the Automations tab -> choose to Edit the flow.
In the Automation workflow editor, you will see the notification informing that the Workflow is live. Since we didn't change anything in the automation workflow settings Publish changes button is inactive, but it will change its state as soon as any modifications are applied.
By viewing the workflow stats, you may also see how many of your contacts are in the sequence at the point of time when you choose to apply some changes.
After you apply the change and click on the Publish changes button, you will see the next Popup message.
Based on this information, we can say that if you only changed the content of the Email message, all contacts that have entered the sequence already will receive the message with updated content.
But after any other changes are applied, you should choose whether you want to discontinue the current sequence or complete it.
If you choose to Discontinue the sequence, all contacts that have entered the workflow will exit, despite of the workflow stage they were at.
If you choose to Complete the sequence, all contacts that have entered the workflow already will complete it according to the old rules.
In both cases, new contacts will enter the modified sequence.