How can I change the arrow head shape in a quiver plot in Matlab 2016 by modifying createLine​sForQuiver​Struct.m?

I have a quiver plot with a lot of vectors and the arrow heads are very difficult to see because they are so small. It would help alot if the angle of the arrow head was wider and the head maybe even filled. I have tried some workarounds, but none was sufficient. For example, following this instruction using annotations as arrows needs a lot of time to generate the figure (too many vectors).

A very promising approach is this. In this answer the shape of the arrows are modified in one function that is called by the quiver function. I think this would resolve my problem, but when I change the values of alpha and beta in createLinesForQuiverStruct.m (which is the only function I found where these values are defined) the apparence of the quiver plot doesn't change. (the file is located in ...R2016a\toolbox\matlab\specgraph\+matlab\+graphics\+chart\+internal\+saveload)

Could someone help me to understand why modifying this function has no effect on the quiver plot?