Security digital signature

[#1]

Is there a way that I can see who has modified a PDF document and when like it is possible on a Word, Excel, etc. document.

As an exemple, I would like to be able to know who signed my document, because I want to make sure that it's truly my manager and not his administrative assistant because she have is digital signature.

P.S. I'm french, so please excuse my bad grammar !

[#2]

Not possible when the assistant has and use the digital signature of the manager.

[#3]

PDF files don't have a "Track Changes" feature, although you can compare versions of the same file.

And a digital signature does not verify the identity of the signer, so no, you can't do either of those things.