What is the most secure way to receive completed forms?

I will be using the forms to collect data that must remain secure.  I plan on emailing the link to each client for the file.  When I selected notification via email, I expected to receive a notification the form had been filled out and then I would go somewhere to retrieve it.  Instead, it sent all the test data unencrypted (even though I had put that I wanted the data encrypted) via my email as text.  

How do I set up a form where no one else can see the results - either through DropBox or Retrieval of form?

If you want to see the form filled information only by you, the best way is to encrypt the form. I have checked the two forms in your account and they are not enabled with Form encryption. Please refer to the guide below that can help you with encrypting the forms.

https://www.jotform.com/help/344-Encrypted-Forms-and-How-to-Use-Them

Please make sure that you have the private key safe since it is not possible to decrypt the submission data in any way if the key is lost.

If you want to receive the data to your DropBox or Google Drive, you may try integrating from the Form settings > Integrations section. 

Hope this information helps! Please get back to us if you need any further assistance. We will be happy to assist.