4. Why does the Adobe Reader show a question mark and a notification about the validity of my StepOver signature being unknown?

By default, each signature in eSignatureOffice is combined with the digital signature of our StepOver certificates. The certificates are not recognized as trustworthy by Adobe, because they have not been created by an official certification authority, but by StepOver itself. In order to make Adobe regard the StepOver signatures as thrustworthy, you either have to install the StepOver certificates to your computer and set them to thrustworthy in your Adobe application or you load a document, which already contains such a signature and use the embedded certificate in your validity settings.

You can find instructions for both possibilities here.