I went into Libre Office to look around, set my font, get a feel for it and it's stuck. I can't use the X to exit any part.
Coming from windows, I went to the system monitor to end the Libre Office process.
I don't find it anywhere. Now I'm very new here so if it's not titled Libre Office as a process (and why not is a good question if you want simple people like me to download Zorin as an OS) I can't possibly guess what it's called.
Can someone tell me what the name would actually be to end this process?
I just want this Zorin OS 16.3 Pro to work correctly. My computer is quite bare so it's definitely a problem with Zorin.
Please, I've read a lot about Linux, I search for solutions, even trying to find the answer to my query in Zorin Forum under "Libreoffice stuck" I didn't find anything. I just need a CLEAR solution.
Big question - did you run sudo apt update and sudo apt upgrade after installing? I normally have issues with certain things - I don't use network while installing; usually breaks my system lol
If you get an unruly app that won't close - open terminal and issue xkill, then hover the X over the window causing grief, left click - poof! Process killed 
I've found that more effective vs opening the task manager and finding the process to kill - I've also found 'end process' doesn't always work as you'd think; or how it turns out for me haha killing does the job though.
I know this is simple. Please bear with me.
I brought up the terminal and issued xkill. It says to to select the window whose client you wish to kill with button 1.
The open software is pictured in my taskbar on the bottom.
I hover over this picture? And where does the application of the button 1 come in?
If you can't click on the window because it's minimized or some other program is taking up the entire screen, you can still press Alt+Tab to cycle through your open programs. Once you've selected the offending program it will be brought to the foreground where you can click on it.
Another option is to open up a terminal window (search for "Terminal" on the applications menu) and run the following command:
ps -ef | grep <name_of_program>
where name_of_program is the running program that you can to search for. If you are unsure try different variations of the name. For example, for Libre Office you can try things like "libre", "office" or "writer" (the equivalent to MS Word is LibreOffice Writer). This would hopefully return something like this:
Next, you want to use the kill command and provide the process ID which you will find in the second column. Notice here there are actually two processes but there's a relationship between them, marked in red in the screenshot. When in doubt always use the lowest number of all, which should be easy to find since the results are already sorted based on the process ID.
If this doesn't work, run the same command again but provide the -SIGKILL option like so: kill -SIGKILL <process_id>. This is the equivalent of plugging the plug and may result in data loss which is why you should try the other option first.
EDIT: This goes without saying but just in case... double, triple and quadruple check that you are entering the correct process id.
That's your left mouse button, primary mouse button 1. 2 would be right click, 3 would be middle click from the scroll-wheel - if you have one; you can also set both 1 and 2 buttons to act as a middle-click, usually for pasting clipboard text.
Can you right click the app in question on the task bar, and choose quit? If not, in System Monitor - highlight the app in question and right click, down at the very bottom - kill. That should end all processes that is currently open --
Be aware - like with my screenshot and Firefox; there are many sub-processes under Firefox. For this example: right click on Firefox (main process), select 'kill' at the bottom of the context menu, and that should stop all processes including sub-processes. If it doesn't - I would reboot at this point.
Also definitely run some updates through either Software Updater, or terminal with sudo apt update && sudo apt upgrade. Much of my fresh installs don't work - update the system, works fine. There might be some revisions that mitigate these issues you're seeing with an update.
That did it, the right click on the task bar and choosing quit.
I knew it would be simple. I just learned about right clicking on the taskbar to get to the system monitor.
Little by little, day by day.
I'm bookmarking this page for sure!
Thanks!
Thanks for your reply! Every time I learn something new. I'm keeping this for future reference.
I moved the marked solution to the first post that states what to do. This can be very helpful to users searching the forum for solutions (just as you initially tried doing.)
I just tested this by launching LibreOffice and then running Task Manager. It did show up in the list as "LibreOffice".
It may be that the name was lost amid the clutter of the long list of running processes. I know that I have missed seeing entries in the Task Manager due to it all being so clustered together.
The learning curve of moving to GnuLinux from Windows can be a bit much all at once. Do not embarrassed. Believe me, when I first moved to Zorin from Windows, I complained a lot, asked a lot of questions and wanted to go back to Windows many times.
It is normal to be frustrated, especially by the simple things. We all felt similar the first times we ever used Windows.
But it is worth every bit of that learning curve to finally break free.
And if you are doing searches and find yourself feeling frustrated; It helps to go ahead and stop and ask here on the forum rather than feed frustration.
Speaking for myself, I would rather type a fast post than wait til you are at wits end and have to type a slower post.