How to set adobe so that preview on taskbar only shows window not tabs?

There is no option to do this because this is not a design behavior nor an irritating user User Interface(UX) flaw of the Adobe Acrobat software, but only Microsoft Windows operating system.

Every other program like Adobe Acrobat, such as Microsft Office (except for web browsers), will annoyingly display in the same way like Adobe Acrobat is showing in the task bar.

In addition, Adobe Acrobat is not a web browser.

The feature that we all have been longing for is called Tabbed Browsing, which is exclusive of web browsing programs (which require an Internet connection).

We've been confusing design behaviors that are entirely different.

If we dig a little more about how computer programs are designed to interact with a specific operating system, it all becomes obvious.

That said, and contrary to the misconstrued popular beliefs in these support forums, Not because we can open and group several  PDFs documents in their own individual tabs inside of a single Adobe Acrobat window working space it means that this is  "Tabbed Browsing".

While convenient, the experience of opening several PDFs inside of one Adobe Acrobat window,  the same is not true for Microsoft Office programs (or any other software intended to run locally in a computer).

Note, that the equivalent to Adobe Acrobat tabs Preference, in  Microsoft Office would be clicking on  "View" ==>> "Switch Windows".

EMPHASIS ON Switch Windows not tabs; meaning that multiple instances of the MS Office program(s) will containerized every opened document on its own separate windowed process.

Let's try, for instance, opening Notepad.exe or Microsoft Outlook, three or more times; and then hover the mouse pointer over its icon on the task bar... what do you see?

Can you tab-browse that program like you would with  Microsft Edge, Mozzilla Firefox or Google Chrome web browsers?  

And can you see the mutliple annoying thumbnail previews for those two programs too?

You'll soon realize that Each document (or instance of the program), they all will be opened (and handled by the operating system not the program that is running locally on that operating system) as individual tasks.

Therefore the opened programs will be displayed in its own container window when you hover the mouse pointer over the corresponding icon in the taskbar.

Is there a way to set Adobe so it does not keep every PDF I open in the tool bar icon ? I open and print alot of PDF's at work and I was hoping there was a way to change the settings so Adobe dosent keep all of them open in the tool bar icon. It is a pain to have to continuously have to close pdf's out....

I have this question too. I want it to show me each reader window, not all the tabs which I've organised into multiple windows at once.

I don't think there is any control of this, in fact I think it's deliberate. I've noticed some apps do this and some don't. For instance, Chrome doesn't do it, but Internet Explorer does do it. So it may be Microsoft's recommendation.