When you configure Generative Answers in Copilot Studio, you expect the copilot to pull responses only from the knowledge sources you specify. Instead, it returns information from other sources or the public web. This behavior defeats the purpose of restricting answers to a curated set of documents, SharePoint sites, or Dataverse tables. The root cause is a combination of default settings and source priority rules that allow the copilot to fall back to broader sources. This article explains why Generative Answers ignores your chosen knowledge source and provides a step-by-step fix to enforce strict source filtering.
Key Takeaways: Enforce Strict Knowledge Source Filtering in Copilot Studio
- Copilot Studio > Topics > Generative Answers > Data sources: Remove all default public web sources and add only your approved SharePoint URLs or Dataverse tables.
- Copilot Studio > Settings > Generative AI > Strictness level: Set to High to prevent fallback to unlisted sources when the copilot cannot match a query.
- Copilot Studio > Publish > Latest published version: After changing source settings, you must publish the copilot for the changes to take effect.
Why Generative Answers Ignores Your Chosen Knowledge Source
Generative Answers in Copilot Studio uses a multi-source retrieval system. By default, the copilot is configured to search across all available sources, including the public web, Bing Custom Search, and any connected Microsoft Graph sources. When you add a specific knowledge source such as a SharePoint site or a Dataverse table, the copilot does not automatically restrict itself to that source alone. It treats your added source as one option among many. The copilot ranks results by relevance and confidence. If a query returns a high-confidence match from a default source like the public web, that result is used even if your curated source contains a valid answer. This behavior is by design to maximize coverage, but it undermines scenarios where you need controlled answers, such as internal HR policies or product documentation.
The problem is compounded by the default strictness level setting. The strictness level determines how aggressively the copilot filters results. At the default Moderate level, the copilot uses results from any source as long as the confidence score exceeds a threshold. Only at the High strictness level does the copilot require results to come exclusively from the sources you explicitly list. Many administrators overlook this setting because it is located in the Generative AI section of the Settings pane, not in the topic editor.
Steps to Force Generative Answers to Use Only Your Knowledge Source
Follow these steps to configure Copilot Studio to ignore all sources except the ones you specify. You must perform both the source configuration and the strictness level change. Skipping either step leaves the copilot with fallback access to the public web.
- Open the Generative Answers topic
In Copilot Studio, go to Topics and select the Generative Answers topic. This is the topic that handles open-ended questions. If you have not created a separate topic, the default system topic named Generative Answers appears in the System topics list. - Remove all default data sources
In the topic editor, locate the Data sources section. You will see a list that includes Public web and possibly Bing Custom Search or Microsoft Graph sources. Click the Remove icon next to each of these sources. The goal is to leave only the sources you control. - Add your specific knowledge source
Click Add data source and select the type of source you want to use: SharePoint, Dataverse, or a custom website. For SharePoint, enter the full site URL. For Dataverse, select the table. For a website, enter the base URL. The copilot will restrict its retrieval to the content in these sources only after you complete the next step. - Change the strictness level to High
Go to Settings > Generative AI. Under Strictness level, select High from the dropdown. This setting tells the copilot to return an answer only when the source is one of the explicitly configured sources and the confidence score is high. If no match is found in your sources, the copilot will not fall back to the public web. It will instead respond with a message like I could not find an answer. - Publish the copilot
Click Publish in the top navigation bar, then select Publish latest version. Changes to data sources and strictness level are not applied until you publish. After publishing, test the copilot by asking a question that your knowledge source should answer and a question that only the public web could answer. The public web question must return a no-answer response.
If Copilot Studio Generative Answers Still Ignores Your Source
Generative Answers returns results from the public web after source removal
This happens when the copilot has multiple Generative Answers topics or when the system-level Generative Answers configuration overrides the topic-level settings. Go to Settings > Generative AI and check the Default response configuration. If it still includes Public web, remove it. Also check each topic that uses Generative Answers. A copilot can have more than one Generative Answers topic, and each topic can have its own sources. Remove public web from every topic.
Copilot returns no answer even though the source contains relevant content
This indicates the copilot cannot index or retrieve the content. For SharePoint sources, verify that the Copilot Studio service account has at least Read access to the site and the documents. For Dataverse, ensure the table is indexed and that the columns you want to search are included in the Generative Answers configuration. You can test indexing by going to Settings > Generative AI and clicking Test. Enter a query and review the Sources section of the response. If the source is missing, the content is not accessible.
Changes to sources do not take effect immediately
Copilot Studio caches source configurations. After editing sources, you must publish the copilot. Additionally, if you are using SharePoint as a source, the indexing process can take up to 15 minutes. Wait 15 minutes after publishing before testing. If the problem persists, remove the SharePoint source, save, publish, then add it again and republish.
Copilot Studio Generative Answers: Default vs Restricted Source Configuration
| Item | Default Configuration | Restricted Configuration |
|---|---|---|
| Data sources | Public web, Bing Custom Search, Microsoft Graph | Only SharePoint, Dataverse, or custom website URLs you specify |
| Strictness level | Moderate | High |
| Fallback behavior | Uses any source with a high-confidence match | Returns no answer if no match is found in configured sources |
| Publishing requirement | Changes apply after next publish | Changes apply after next publish |
| Use case | General knowledge copilot | Internal policy, HR, or product documentation copilot |
After applying the restricted configuration, your copilot will ignore any source that is not in your explicit list. The High strictness level ensures that even if the copilot finds a high-confidence match from an unlisted source, it discards that result. You can verify the restriction by asking a question that exists only in the public domain. The copilot must respond with a no-answer message. If it returns a public web result, revisit the settings and confirm that no other Generative Answers topic has a broader source list.
Test the copilot with a set of queries that cover the content in your knowledge source and queries that are out of scope. Use the Test pane in Copilot Studio to review the exact sources cited in each response. The Sources section shows the URL or table name that the copilot used. If you see a source you did not configure, repeat the removal and strictness steps. For advanced control, you can also define a custom prompt that instructs the copilot to only use the listed sources, but the High strictness level alone is sufficient for most scenarios.