Word 2010.
I am confounded by instructions to customize a QAT for a custom template. I have opened the template I'll call Fred.dotm (which is in a folder on my desktop), customized the QAT, and exported the customization to a UI file on my desktop.
After closing the template and either re-opening it or a new document from it, I see the customized QAT. If I open options/customize QAT, the list is blank for All documents, but I can select the Fred.dotm and the custom list appears.
If I then open a document based on Normal.dotm, the QAT is clear, so I rebuild my stand customization, leaving "for all documents" selected. So far, so good.
However, when I then open Fred again, I see a combined toolbar of both. If I try to import the Fred UI doc I exported previously, I get a message saying "Replace all existing Quick Access Toolbar customizations for this program?"
If I say yes, my QAT in Fred returns to the customization I created for it, but the list for All documents is erased. Fred is fine, but my Normal.dotm QATis blank. If I rebuild it, I get the combined tool bar in Fred.

What am I doing wrong, please?

As far as I can tell, you are doing nothing wrong. QAT customizations are stored either in a separate file or in a template. I would expect to see both global and template-specific QAT buttons in Word.

__________________
Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional

The QAT customisations on Normal are always visible. The QAT customisations in Fred are only visible when Fred is loaded.

You can't selectively hide Normal's QAT customisations just because Fred is loaded. If that is what you want, you need to place the QAT customisations into a different template and load it as an add-in so you can selectively load/unload that add-in whenever you want those customisations.

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Andrew Lockton
Chrysalis Design, Melbourne Australia

See Modifying the QAT and Ribbon in Microsoft Word.

QAT modifications saved for all documents are stored in a special file. They are visible in all documents/templates.
QAT modifications saved in the normal template are visible in all documents/templates.
QAT modifications saved in other Global Templates are visible in all documents/templates.
QAT modifications saved in a document template are visible in that template and documents attached to that template.

You can have multiple files that hold QAT modifications active at once. I've have at least five global templates that hold QAT modifications related to resources in those templates. I also have other document templates that have QAT modifications related to resources in those templates or tasks done in documents based on those templates.

I can't conceive of a reason that I would store QAT modifications in the normal template. I do not store macros with which I would use a QAT button in the normal template. Storing them in a different global template makes them easily portable.