How do I save form submission to my computer

How do I save the form when the submit button is selected to a folder on Dropbox?

You can save your form submissions to Dropbox automatically:

https://www.jotform.com/help/77-Upload-to-Dropbox-with-JotForm

If you would like to backup your data to your computer in Excel format, here is how to do so:

https://www.jotform.com/help/44-How-to-Export-Form-Data-to-Excel