Adobe Premiere Elements 2018: Motion Titles Graphics colour change

Hi, I am new to creating videos on Adobe Premiere Elements 2018 and I am struggling to change the colour of my general motion theme. I am using the formal general theme and it gives me a choice of 8 colours under graphics, however none of these colours is the one I want to use (I want dark green and it only gives me a light green option). Does anyone know how I can change the graphics colour to the one of my choosing?