Hi, Claude
I don’t think this is something you can force back as a Windows default voice in the usual Windows 11 voice settings. “Microsoft Ava Multilingual Online” is one of the online/neural voices used by Microsoft’s Read Aloud/Immersive Reader service, not the same as the older installed Windows voices like David, Zira, etc.
First, I would check inside Word itself, not only Windows Settings. Open Word, go to Review, start Read Aloud, then select the small gear icon in the Read Aloud controls. If Ava is still available for your account/build, it should appear under Voice Selection. Do the same in Outlook from Read Aloud/Immersive Reader voice settings.
If it is missing there too, it is recommended that you sign out of Office completely, restart the PC, sign back into your Microsoft 365 account, and make sure Word/Outlook are fully updated. Also check that you are online, because the better natural voices usually depend on Microsoft’s online service.
If Ava still does not appear, then Microsoft may have removed or changed access to that specific voice in your current Office version. As a workaround, it is suggested that you try Read Aloud in Microsoft Edge or Word for the web, since those sometimes show the online voices when the desktop app does not.
Thank you for your patience in reading, I hope this information has been helpful to you.
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