# Set user Duckling configuration


> Sets Duckling (instance) configuration for a service account or user account. Requires 'Admin' role.

::::info
  This endpoint is used to configure settings for service accounts and user accounts, including Duckling sizes.
  For a complete walkthrough of service account management, see [Create and configure service accounts](/docs/key-tasks/service-accounts-guide/create-and-configure-service-accounts/#configure-ducklings).
::::

::::caution[Username Parameter]
  When configuring a service account, ensure the `username` in the path (`/v1/users/:username/instances`) is the specific username defined when creating the service account. The endpoint path uses `instances` for legacy reasons but configures Ducklings.
::::

`PUT /v1/users/{username}/instances`

Sets Duckling (instance) configuration for a service account or user account. Requires 'Admin' role.

::::note
  Authentication for this endpoint requires an Admin token. This endpoint configures Duckling sizes and read scaling pool size. Use the token endpoint to create read scaling tokens.
::::

::::note[Cooldown behavior]
  `cooldown_seconds` cannot be set on **Pulse** instances — sending it for a Pulse `read_write` or `read_scaling` returns `400 "cooldown_seconds cannot be set for Pulse instances"`. For larger sizes, omitting `cooldown_seconds` applies the default of `60` seconds (the minimum); when set explicitly it must be in the range `60`–`86400` seconds.
::::

## Request


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## Docs feedback

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