I've designed a new form and at the beginning of the wizard I put an e-mail address (firstname.lastname@example.org) for the replies. At the end of the form I've put a "send button" where I've specified a new e-mail address (email@example.com).
After the distribution process, I distribute the correct file named yyyyyy_distributed.pdf and at the moment of sending it back filled it's proposed the originary address (firstname.lastname@example.org) and not the modified one (email@example.com). It seems it remebers the first settings and it's confirmed by the subject of the e-mail: if I leave the field of the subject empty it uses the same personalized message I used in the first form I did.
Other infos: I'm trying to distribute the file in order to collect the answers by e-mail. Have the same result trying to distribute via mail or save for next sending.