Modifying sign in form

I have set an automatic timeout for a session, and for security reasons I want
remove the ‘Stay signed in for 14 days’ option from the core login page. I have tried adding the form.php file to the Application\Authentication\Concrete folder and modifying it but nothing changes.

If you copy the form.php from concrete/authentication/concrete to application/authentication/concrete it should work (assuming you’re using the standard ConcreteCMS authentication).

Make sure your directory names are all lowercase and you clear the cache on your site.

I checked and one of the directory names had a uppercase starting letter!
I have modified the form.php file and it works now without the ‘stay signed in’ checkbox and line.
Many thanks you for your help