Logout flow cannot redirect to right url

When I create an Oauth2 Client with terminal, I added --post-logout-callbacks <url> and rechecked with get clients command.
Logout flow work fine except cannot redirect to above <url>. I got this error:

" The Default Post Logout URL is not set which is why you are seeing this fallback page. Your log out request however succeeded.

You are seeing this page because configuration key urls.post_logout_redirect is not set."

Please help! Thanks.

refers to the configuration value in hydra.yml or env var URLS_POST_LOGOUT_REDIRECT=

Oh I see, thanks.
But what if we have many logout redirect for many different clients?
Because if we set this in hydra.yml or in env var, we do it when run hydra and after that we create clients, each client has separate logout url redirect, so how can I do that?

Check out our logout guide ( https://www.ory.sh/hydra/docs/implementing-consent#user-logout ) to learn the different scenarios and cases. The client’s redirect URI can only work if e.g. an id_token_hint is supplied and so on.