hiya, on the 'comment editor' you can adjust the arrow width, length, colour etc
Scid vs. PC arrow size problem.

if you can't see the arrow width adjuster, drag the windows down to make it larger and it will be there

try splitting the screen, not sure if that makes a difference....here is what mine looks like
the way to split the screen is to right click on a window and select, move to bottom. So for you, try moving the stockfish window to the bottom
The arrows I draw are so tiny, and I don't know how to fix this. There were couple of other posts in multiple sites but nothing helped me so far. Do you guys have any solutions for this? I also saw something about the program supporting ChessBase arrow extension or sth, but I couldn't find anything about that too. Thanks.