Customer Community licences use the OWD and another feature on the Community of the Sharing Sets. Salesforce documentationSalesforce documentation
To create a Sharing Set goI have been able to Setup>Build>Customize>Communities>Community Settingsreproduce the problem and select Sharing Sets, you can then createhave found a work around - if the Sharing Sets required foruser creates a case from the objects. The permissions that you grant can only extend what is onAccount page using the OWD, so for example if Cases are privatenew button on the external sharing model they can be made Read Only or Read/Write for Community Users who are linkedrelated list it allows them to the same Account assave the Casecase.
Sharing sets can be shared with particular Profiles
While if I try from the Cases Tab and use New then add the account in the Community as belowlookup I get the problem.
