The icon was selected automatically - I didn't see an option to pick one. Yes, I am sure that the toolbar/icon is the custom one that I created for the line wrap toggle. When you click it, the line wrap is toggled. Additionally, as shown in the attached screenshot, you can see that the user script name "Toggle Line Wrap" is shown in both the icon dialog (that pops up when the icon is hovered) and the user script name in the Toolbox on the left-side of the screen.
As an aside, the toolbar was added automatically to the "Toolbar - Right." I didn't see an option to select which one it was added to and I don't know how to move it to the "Toolbar - Left." I'm not sure if this affects the issue.