Below threshold Windows Aero will show thumbnails. But over threshold, because the thumbnails would be too small, it’ll show list instead.

Set:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Taskband\NumThumbnails

to DWORD(32bit) 10 or whatever number you want.

Reference: tenforums.com : Windows 10: Change Taskbar Thumbnail Threshold to Show List in Windows 10

• https://www.tenforums.com/tutorials/20989-change-taskbar-thumbnail-threshold-show-list-windows-10-a.html