User Congregations
You'll find the User Congregation record under the System Setup folder.
From here, if you configured your views and filtered pages to honor User Congregations, you can add, remove, or update the User's permitted Congregation(s) so they see only records for that Congregation. If you don't specify Congregations, the User can see all Congregations.
You can primarily use this with the Batch Manager Tool. See Values and Defaults for details.
Note: Previously, User Congregations was also a sub-page called "Congregations Allowed" on the User record. However, with the addition of Global Filter features, we removed the "Congregations Allowed" sub-page. You can still use this feature and manage it from the User Congregations page. Eventually, the Global Filter features will fully replace the User Congregations feature. If you have not previously set up User Congregations, we recommend that you instead leverage Global Filters.