I have a simple html form as follows:
You can disable right click and the F12 button to prevent the issue. Follow the below links.
1.) Disable right click 2.) Disable F12 button
There is nothing stopping a user from changing values in browser by using firebug/inspect element/ what ever..
What we can do is checking our values on server side and prompting user if they mismatch.
Shouting again ..