Update from Ver. 4.04 to 4.06 was easy, except I didn't delete the old folder beforehand, thinking it would not need it if no longer a Beta.
Update from 3.1.9 took out some style settings, but fairly easy to fix as I had encountered this previously on another site. When I checked the display of the form form on a mobile, I found many style issues that took some time to sort out, but finally am satisfied with the result.
When I tried to send e-mails, I got a message that the CAPTCHA entered was incorrect. After trawling through the Support pages, I thought it might be a sessions issue and was about to start debugging. I went to the Advanced form and E-mail settings and found an error message about permissions. The Sessions box was not checked so I checked it and the error message disappeared. I could the send mail, but not attachments. In FTP I changed the permissions to 777 and no more problems.