I am a new KDE Plasma user(version details on the bottom) and i am wondering what is the correct way to add shortcuts to the panel. So far i have created a second panel which resides on the top of the screen and i drag and drop shortcuts after i search them on the start menu.

I am using a second monitor and i want to enable/disable it from the displays menu instead of just pulling the HDMI cable and having windows bugged out (happens some times). So i need a shortcut on the "Displays" menu in my panel.

Issue 1:
I tried dragging the "Displays" icon to my panel but nothing happens apart from an 1-item menu appearing with a "fetching file type... " choice. If i click on it, nothing happens. Am i doing it wrong? Creating a desktop shortcut of "Displays" does render a default KDE icon instead of the one in the start menu.

Issue 2:
Just before i wrote this post, one of my shortcuts icons had disappeared (it was still clickable and working) and i had to remove it and add it again on the panel.

Issue 3: (this one is a bit off topic but i'd rather post it here)
Sometimes the whole plasma work space breaks and it is not updating and things are not responding. I have tried to restart plasmashell via command line without success. What is the correct way/commands to get my shell working without a system reboot?

Ubuntu 18.04 upgraded from 16.04.
KDE Plasma Version: 5.12.6
KDE Frameworks Version: 5.44.0
Qt Version: 5.9.5
Kernel Version: 4.15.0-34-generic
OS Type: 64-bit
Nvidia drivers: Nouveau because nvidia's proprietary have some issues.

I think the issue here is that one cannot add shortcuts to subcategories of settings that reside inside the System settings yet.