Changing schema-registry compatibility level in Confluent 5.3.1 version not working

hello Team,
Does anyone know how to change schema-registry compatibilitylevel in confluent 5.3.1 version I tried this curl -X PUT -H “Content-Type: application/vnd.schemaregistry.v1+json” --data ‘{“compatibility”: “BACKWARD”}’ http://localhost:8081/config/ but did not work still says {“compatibilityLevel”:“NONE”}

I have always done commands with content type of just JSON

curl -X PUT <http://localhost:8081/config> -d '{"compatibility": "NONE"}' -H "Content-Type:application/json"