Change external store ID - Store Management - Mercado Pago Developers
Which documentation are you looking for?

Do not know how to start integrating? 

Check the first steps

Change external store ID

There is also the possibility to create an external ID (external_id) for a certain store. This field is optional, but can be used as an identifier for the order management software system.

To enter the value of an external ID in a store, perform a PUT sending the store_id and access_token (generated by the OAuth authentication process) to the endpoint /proximity-integration/stores/{StoreID}/ external_id. See Security for more information about OAuth.

Important
You will also be able to consult the information of a store through its external ID. For that, just send as request parameters the user_id related to the store, the external_id and the access_token. Check more information in the API Get store by external ID .