I have an php variable like this:
PHP Code:
$php_value = \'Am from PHP\';
And I want to be able to change this variable with jQue
You can't.
By the time the page has been delivered to the browser and the JavaScript has run, the PHP program that generated the page will have finished running and the variable will no longer exist.
JavaScript will allow you to send new data to the server (Ajax), where the server could store the data somewhere (a database is usual), and read the response.
JavaScript will also allow you to modify the page in in the browser (DOM) (including with the data included in the response for an Ajax request).