Many business or other practical applications need digitally-signed documents to be verifiable for months or years after signing. However, the signed document can be no longer verifiable if the signer’s certificate has expired or been revoked, or with some other reasons.

1. Open the PDF containing the signature, do one of the followings:

By default, Foxit PDF Editor will check the certificate revocation status while validating a signature if the certificate used to sign a PDF file chains up to a certificate designated as a trusted anchor. Revocation checks are performed based on the revocation information embedded in the digitally signed PDF document, the digital signature, or the Certificate Revocation List (CRL). To view the certificate revocation information, please do the following: 

By default, Foxit PDF Editor verifies signatures when the document is opened. An icon appears on the left top of Signature Validation Status message box to indicate the signature status. The signature state appears in the Signature Panel.

The signature of a certified or signed document is valid if you and the signer have a trust relationship. The trust level of the certificate indicates the actions for which you trust the signer. 

To set the trust level: 

By default, Foxit PDF Editor will verify signatures when the document is opened, and will check the certificate revocation status while verifying signatures. If you want to change the setting, please go to File > Preferences > Signature, and uncheck the corresponding option in Signing & Verifications group. For more information, please refer to “Signature Preference”. 

To modify a signature after signing the document:

1. Right-click the signature with the Hand command and choose Clear Signature. The signature will be cleared and only a blank signature field will be left.
2. Click the blank signature field with the Hand command, and create a new signature. See also “Creating signature appearance”.

To delete a signed signature:

A PDF is signed to indicate your approval. The signature is flattened, so it cannot be resized and moved after signing the document. Multiple people can sign a PDF more than once. When you sign a document, your digital signature appears in the signature field. The appearance of the signature depends on your preferences.

You can set the appearance of your digital signature by selecting different options in Configure Signature Style dialog box. For example, a signature can include an image of your handwritten signature, a company logo, or a photo, date, reasons for signing, and so on.

You can move, resize and delete signatures before signing the document, but you aren’t allowed to change certificate and appearance of certificate.

1. To move a signature

Select the Select Annotation command or the corresponding tool, put the pointer over the signature, click and drag the signature to another place you like.