Need help with istio grafana configuration on kubernetes

Hi i have installed istio on kubernetes which installed grafana , i wanted to add oauth configuration to grafana using keycloak, i tried adding grafana.ini on configmap created by istio but it didnot work. Can someone please help me?
i added:

enabled = true
client_id = YOUR_APP_CLIENT_ID
client_secret = YOUR_APP_CLIENT_SECRET
scopes =
auth_url =
token_url =
api_url =
allowed_domains =
allow_sign_up = true

cloud provider: AWS