As an Admin, you can update a Managed Audience at any time, but you should be aware that if the audience is currently being shared, any updates could affect campaign recipients where the audience has been selected.

To update a managed audience, start by navigating to the Audiences menu and select the audience you want to update. From here:

• Within the audience, make your updates (e.g.: add new filters, remove or update existing filters).
• Select Save Audience
• You'll be reminded that changes may affect recipients in campaigns where this audience is selected. Confirm that you understand and accept this by selecting Update.