serverless config credentials --provider provider --apihost apihost --auth auth
--provider or -p The provider (in this case openwhisk). Required.--apihost or -h The openwhisk_apihost. Required.--auth or -a The openwhisk_auth. Required.config:credentials:configserverless config credentials --provider openwhisk --apihost openwhisk.ng.bluemix.net --auth username:password
Credentials are stored in ~/.wskprops, which you can edit directly if needed.