Does use of Fill & Sign, once saved, always lock all pdf fields?

I'm not aware of different kinds of signature fields. They are digital signature fields, accessed from the Prepare Form tool. From what I can tell, if I use the Fill & Sign tool, I can select my signature and place it anywhere on the document—on a field, on a signature field, on a line, in blank space, etc. The signature image just overlays the document. And then saving locks all of the fields. I haven't seen or altered a setting that causes this behaviour, which leads me to assume: if a user has pro acrobat and thus access to Fill & Sign, they have the ability to place this kind of signature anywhere on any document. Am I wrong?

That works for Digital Signatures, thank you. 

But I'm asking about the Fill & Sign tool, where users create and paste an image of their signature, essentially wherever they want. In the case of Fill & Sign, it appears to me the document always locks once one signature is added and the doc is saved. Am I wrong?