Welcome to the forum!
As far as I can understand your message, you downloaded Inkscape from the Windows Store? Inkscape is not a Windows App. It's a standalone program which has been provided to the Windows Store (for some reason which I don't really understand - convenience maybe).
What was it specifically that you did, which you thought would sync your preferences and extensions on all your other computers? As far as I know, there's no way to do that. As far as I know, each Inkscape installation needs to be configured individually.
It should be possible to copy the preferences.xml file from on computer, and paste it into all the others. And you should also be able to do the same thing with the extensions folder. (And other resources too - filters, palettes, etc.)
But if you add a new extension to one computer, you would have to copy/paste the extensions folder into all the other computers, again. There's no way to connect the Inkscape program installed on one computer, to Inkscape installed on other computers.
If Windows 10 provides such a feature as syncing different Windows computers, it probably is restricted only to Windows apps. And Inkscape has no association with MS or Windows. It's a standalone program.
As for the malfunctioning you've experienced, I would say undo whatever it was you did. If that doesn't fix Inkscape, then I would uninstall Inkscape, and then reinstall it. But this time, don't try to sync Inkscape with other computers. You should still be able to get it from the Windows Store, but just don't try to sync it.
(I don't know if there is any kind of warning about this, in the Windows Store. But maybe there should be, if it causes the kind of problems you mentioned?)
