Brush size selector in Terrain Painter... Can you fine tune it in update ?

I find it very difficult to select 2,3,4,6,7 for brush size. I tried changing mouse sensitivity to give more fine tuning and tried to change the user interface in preferences. I did not see where that could be changed.
Thanks if anyone knows a way to do it.

 

Ctrl is the key https://www.beamng.com/threads/world-editor-2-0.61035/page-9#post-1311867