Update application-management-certs-faq.md

Adding a question to resolve ambiguity around the same SAML certificate being used in multiple apps.

Author: jsoveral

articles/active-directory/manage-apps/application-management-certs-faq.md

@@ -82,3 +82,7 @@ To renew an application token signing certificate, see [How to renew a token sig
 ## How do I update Azure AD after changing my federation certificates?
 
 To update Azure AD after changing your federation certificates, see [Renew federation certificates for Microsoft 365 and Azure Active Directory](../hybrid/how-to-connect-fed-o365-certs.md).
+
+## Can I use the same SAML certificate across different apps?
+
+When first time configuring SSO on an enterprise app we do provide a default SAML certificate that is used across Azure AD. However, if you need to use the same certificate across multiple apps that is not the default Azure AD one, then you need to use an external Certificate Authority and upload the PFX file. The reason is that Azore AD does not provide access to private keys from internally issued certificates.