Check out that post here: Edit Windows Virtual Desktop Properties in the Azure Portal.
If you prefer using Audio & Video Redirection instead of Media Optimizations, you can now even configure that without PowerShell (if you created your tenant via the Azure Portal). Microsoft recently updated Teams to make it even easier to use audio/video within WVD! While the blog post below may still be useful, check out our more recent post on Enabling Audio and Video for Microsoft Teams on Windows Virtual Desktop using Media Optimizations.