edit /etc/lightdm/lightdm-gtk-greeter.conf and edit "indicators" or "show-indicators" option: add "sound" to it. Note that if you add it at the end of the line, it will appear to the right of the power button on the lock screen.
** Changed in: lightdm-gtk-greeter (Ubuntu) Status: New => Fix Released -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1458933 Title: No volume control on screen lock - Volume goes to 100% To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm-gtk-greeter/+bug/1458933/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs