Hi Frederick, if you right-click on a color swatch in the Styles section of the scene browser, that will set the "active style" which is the style color that will be assigned to newly drawn objects.

There are other options for adjusting the display though, under Options > View > Colors > "Edge colors".

There you can set edges to always be displayed in one fixed color instead of the style color, and another option is you can set it to a darker or lighter version of the style color and you can adjust the dark/light factor there.

- Michael