These disable the page and media files cache. The credentials are cached nonetheless. As I told you, it would be stupid for a browser not to cache them. Think about going to your site's back-end and having to enter a username and password. Next click you do, again asks you for a username and password. One more click and it asks you for a username and password. Click on the next page and it again asks you for a username and password. Are you pissed off yet? Browser makers know that you are that's why they cache the credentials. Please note that I really do know what I am talking about. If you don't believe me, despite you –by your own tests– having verified what I am saying, you can always not ask for my assistance and try to find out a solution by yourself. Firefox has all the necessary tools, including Firebug, to debug HTTP connections. This is what I did (in FF and Chrome) when you reported your issue. I made sure it's not a problem with the .htaccess generated and gave you the troubleshooting steps. So, from now on, you know how to debug this by yourself.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!