How to reduce OSD time-out?

The thread Dismiss Windows 8 Volume Box (top left corner) describes the problem :

When adjusting the volume in Windows 8.1, a box appears at the top left corner of the screen. This box sticks around for ~13 seconds before it fades away. If you attempt to dismiss it by click on it, it switches to the music app.

This is the accepted answer, as adapted to Windows 10 :

1. Open Start menu > Settings
2. Click Ease of Access > Other options
3. Change the drop-down box of "Show notifications for" to the preferred time.

Another possible setting is :

1. Open Control Panel > All Control Panel Items
2. Go to Ease of Access Center > Use the computer without a display
3. Set "How long should Windows notification dialog boxes stay open"

You can reduce the duration, but you can't go below 5 seconds.

1. Open Start menu > Settings
2. Click Ease of Access
3. In Display tab > set "Show notifications for" what ever you want (value > 5)

You can set the duration to something other than the values selectable in the menu by changing the appropriate key in registry (with regedit):

MessageDuration under HKEY_CURRENT_USER\Control Panel\Accessibility

Source is option three from here: https://www.tenforums.com/tutorials/6175-change-how-long-show-notifications-windows-10-a.html