View digital signature and certificate details – Microsoft Support

Click File > Info > View Signatures. In the list, on a signature name, click the down-arrow, and then click Signature Details. From the Signature Details dialog box, you can determine if the signature is: Valid The signature is current. The certificate is trusted, and isn’t expired or revoked. Invalid The certificate is revoked or the content …

https://support.microsoft.com/en-us/office/view-digital-signature-and-certificate-details-76ba00cb-1e58-42aa-8717-0caee76bb3cf