To adjust branch settings select the Tree settings Options Panel tab.
The following settings are available:
Here you can change the size of the tree using Expansion slider and the curvature of the lines using the Curvature slider.
Slider position returns to original position by double click on field name or on the sliders.
Here you also can select the color and the line width of the tree branches.
Note that when a clade has been selected the branch settings Color and Line Width are applied to the clade only.