Are those digital signatures signed with certificates? If they are then it means that certificates with which these signatures were signed have expired. Each certificate has an expiration date. The person who signed PDF could have chosen to include signature revocation status in the document but apparently declined that. Had these PDFs included revocation status, the signatures in them would have validated properly. Just in case revocation status is included, make sure that the "Verification Time" preference is set to the "time when signature was created" (which is default since Acrobat 9.1). You cannot validate signature signed with an expired certificate at the "current time". Acrobat X and later has the ability to add Verification Information (includes revocation status) post-signing but only at a time before certificate's expiration and only for valid signatures. If you are past this point there is nothing you can do.
If these are not digital signatures then what they are and what do you mean by expiration?
Below is an example: I just signed this form this morning. I'm a fairly novice user, but from what I can tell here are a couple of issues.
- the valid from date is set prior to the actual signing of the document (signed on the morning of 10/16/15) and was not set by me
- the valid to date seems to be set six months from the valid from date and was also not set by me
I also find that I'm not able to edit the intended usage during signing.
Am I able to manage this data myself prior to signing or does this happen automatically?
A certificate acceptable for signing must have either "Digital Signatures" and/or "non-Repudiation" in Intended Usage. Your certificate has none. It looks like this is a self-signed certificate, so create a new one that includes "Digital Signatures". If you do that in Acrobat the creation dialog allows to to select what this certificate will be used for. Digital Signatures and Encryption are the default choice.