hi, you can open a second window with the keyboard shortcut ctrl+n. please note that you should also [https://www.mozilla.org/firefox/update/ update firefox to the latest version] as soon as possible - you are using an outdated version [https://www.mozilla.org/security/known-vulnerabilities/firefox.html affected by numerous known security vulnerabilities] which will put the integrity of your system and your personal data at risk!

This works also when I am logged in somewhere else on the network? My settings are shared on both locations

in this case you might want to try http://kb.mozillazine.org/Opening_a_new_instance_of_Firefox_with_another_profile