Update proxy authentication instructions for VS (#39578)

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Sharra-writes <sharra-writes@github.com>

Author: 3 people

content/copilot/how-tos/configure-personal-settings/configure-network-settings.md

@@ -71,7 +71,16 @@ If you have configured a proxy but are still encountering connection errors, see
 
 ### Basic authentication
 
-{% data variables.product.prodname_copilot_short %} for {% data variables.product.prodname_vs %} does not retrieve authentication credentials from the Windows settings. If you need to authenticate to a proxy, you can include your credentials in the proxy URL (for example: `http://USERNAME:PASSWORD@10.203.0.1:5187/`), then set this URL as one of the supported environment variables listed in [Proxy settings for {% data variables.product.prodname_copilot_short %}](/copilot/concepts/network-settings-for-github-copilot#proxy-settings-for-copilot).
+While {% data variables.product.prodname_copilot_short %} for {% data variables.product.prodname_vs %} reads the proxy settings from Windows, it does not retrieve authentication credentials from those Windows settings.
+
+If you need to authenticate to a proxy, you can try one of the below:
+1. Enable passing default proxy credentials by setting the environment variable `COPILOT_USE_DEFAULTPROXY` to `true`. 
+   - **Windows example**: Open the Command Prompt and run the following command:
+     ```
+     setx COPILOT_USE_DEFAULTPROXY true
+     ```
+     This sets the variable permanently for your user account. Restart any applications that need to use this variable.
+2. You can include your credentials in the proxy URL (for example: `http://USERNAME:PASSWORD@10.203.0.1:5187/`), then set this URL as one of the supported environment variables listed in [Proxy settings for {% data variables.product.prodname_copilot_short %}](/copilot/concepts/network-settings-for-github-copilot#proxy-settings-for-copilot).
 
 {% endvisualstudio %}