If you've already created a membership, you can edit the options for this membership. Any changes will only affect new sales, existing memberships will not be affected.
Memberships that haven't been sold yet can have all of their attributes edited. Once a membership has been sold to one or more users, however, you won't be able to change the joining fees or inclusions (although everything else is still editable).
Edit an Existing Membership
To edit a membership you've already created:
Go to Settings > Memberships.
Select the correct membership tab based on the type of membership (recurring, pre-paid or trial).
Select Edit.
Make your changes and then select Update.
Edit a Membership That Has Already Been Sold
Once a membership has been sold, it's not possible to edit the included credit packs or products.
If you want to change the joining fees or inclusions for an existing membership, you can create a new version of the membership and change your users onto that new membership.
To change a membership that has already been sold:
Create a new membership that includes the joining fees and inclusions that you need.
Delete or archive the existing membership.
Change the membership on the user's account to the new membership.