We use Adobe Acrobat 9. I sign my docs with a digital signature I created through Adobe (the first time I used it I "placed" my signature, I was required to create a password and confirm by email it was me, now I just place my signature and enter the password and it shows as valid with timestamp). The signature shows as valid when I view it in Acrobat. But when I (or anyone) views it in Adobe readers, it says the signature is invalid and certificate is not trusted. Please help
Are the certificates available on the other systems?
Is the signature status Invalid or Unknown? It could be that you trusted your signing certificate on your Acrobat installation but other people don't. They need to trust your certificate (or its root, but from what you wrote you created a self-signed certificate in Acrobat, so there is no root) in order to get the signature status as Valid. They do not need your certificate as it is embedded in the signature.