Adding a new audience to an already initiated campaign
You've created your campaign and sent it out, but suddenly you realise the audience is wrong!
Whilst we don't recommend doing this as common practice, you can change the audience after initiation. Just be aware that it will skew your campaign statistics.
Change the Audience
You'll see on this live, initiated campaign, that you can still select and count an audience group.
To change it, simply select the desired group and count it.
You will then have to re-send to the campaign audience.
Of course, you could always create a separate campaign copy and change the audience as it will have not been initiated yet.