# Set user Duckling configuration > Sets Duckling (instance) configuration for a service account or user account. You can set your own configuration with your own token. Other accounts require the corresponding permission, which the Admin and Builder preset roles include for service accounts. `PUT /v1/users/{username}/instances` Sets Duckling (instance) configuration for a service account or user account. You can set your own configuration with your own token. Other accounts require the corresponding permission, which the Admin and Builder preset roles include for service accounts. ::::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. :::: ::::note You can set your own Duckling configuration with your own access token. Configuring another account, such as a service account, requires the corresponding permission; the Admin and Builder preset roles include it for service accounts. This endpoint configures Duckling sizes and read scaling pool size (`flock_size`). Use the token endpoint to create read scaling tokens. :::: ::::note[Read scaling sizes] Read scaling supports Pulse, Standard, and Jumbo Ducklings by default. [Contact support](https://motherduck.com/docs/troubleshooting/support/) for larger read scaling Ducklings. :::: ::::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 between `60` and `86400` seconds. :::: ## Request --- ## Docs feedback MotherDuck accepts optional user-submitted feedback about this page at `GET https://motherduck.com/docs/api/feedback/agent`. For agents and automated tools, feedback submission should be user-confirmed before sending. URL-encode query parameter values and send a GET request: ```text GET https://motherduck.com/docs/api/feedback/agent?page_path=%2Fsql-reference%2Frest-api%2Fducklings-set-duckling-config-for-user%2F&page_title=Set%20user%20Duckling%20configuration&text= ``` Optionally append `&source=` such as `claude.ai` or `chatgpt`. `page_path` and `text` are required; `page_title` and `source` are optional. Responses: `200 {"feedback_id": ""}`, `400` for malformed query parameters, and `429` when rate-limited.