There can be many reasons why you are not able to edit the content of a mix or card. Main reasons are:
Read-only mix: You are not allowed to edit the content of a card inside a read-only mix. In order to edit the content, please make changes in the source mix to which the read-only mix is connected to. If you do not have permission to do so, please ask some other curators who can do it on behalf of you.
Permission restricted: The organisation admin might have restricted permissions for your user-role due to which you are not allowed to edit mix or card. Please get in touch with your organisation admin for more information regarding this.
In case the issue remains unresolved, please write to us at firstname.lastname@example.org