Click on the three dot icon on the right and select 'Edit Membership' in the dropdown menu.
Once you've selected the membership you wish to edit the setup page will load. On this setup page navigate down to the dropdown under the title "Membership Domain":
If you's like to select a new domain name, click on the gray dropdown on the right. A list of available domains will open.
Select the new domain you would like to use for your membership.
Your membership will now be published under this domain.
Note: If you don't see your custom domain within this domain list or you wish to add a new domain. Go to our training on connecting a new domain to your Member App account located here.