Here you should (again) think about what is happening where.
When you load the page into your browser it is local on your client. When you submit the data, your browser is sending that (form)data to the server (you could read about HTTP-REQUESTS). Up to your browser you can be able to edit that local code before you are submitting the form. This will not change the sourcecode on the server, but in your local cache. Try F12 for chrome or firefox (firebug)