JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Unfortunately, you can't edit the existing Dropbox integration when it comes to changing accounts, but you can remove it and re-integrate again to have the correct one. Here's a guide on how to integrate Dropbox: http://www.jotform.com/help/77-Upload-to-Dropbox-with-JotForm.
I hope that helps.