change change the number of taskbar thumbnails to show before the become s stacked list in windows 10

i am trying to change the number of taskbar thumbnails to show before the become s stacked list in windows 10,i have a 1920X1080 screen so the limit was 16,i created and modified the regedit key "NumThumbnails" and it worked until 19 thumbnails instead of 16 and then it became again a stacked list.