Choose any of the predetermined themes or you can use the custom theme to modify individual foreground and background colors.
Click save. Go back to the property page and refresh it to see the new colors take effect.
Changing the fields displayed on the stacking chart and hover
Go to Setup | Create | objects
Scroll down the list and click on Space
Click on the Field Sets link on the top
Click Edit on the left of the field Stack Chart Fields
Drag and drop the fields to change the In the Field Set list and rearrange them. The top two are displayed on the stack chart and a max of six fields are displayed in the hover. Note: Please limit the In the Field Set list to five fields to preserve the aesthetics of the hover and the chart