The video below shows the process of How to Change the Font Colour in a Sidebar (click the button on the bottom right of the video to expand the view). You can also follow the screen shots and steps below this.
3) A list of your sidebars is displayed. Click on the title of the sidebar you wish to edit.
4) Select the text you want to change
5) Click on font button for the colour options and select the chosen colour. If you cannot see the shade you like, click on More Colours and choose from some of the alternatives.
6) Your highlighted text will automatically change to the selected colour.