Text colors can be changed by using the color box in the toolbar above the template.
Select the text on the template.
Select the color box in the toolbar above the template. This will load the color picker in the left-hand side bar.
Select one of the colors template colors listed or choose a color from the color picker.
If using the color picker, the hex color code can be typed or pasted into the color code box. Or the colors can be changed using the multi-color bar on the bottom of the color picker. Then drag the small circle inside of the color picker. As colors are selected in the color picker the text box will update with the current selection.
Note: Only one color is supported per plain text box. Menu text supports one color per field type (example: all item names can be red, all prices can be blue).