This is the most precise way if you wish to control all aspects of object and it styles colors.
Select an object(s), then click Styles menu item on the Edit Toolbar. The following styles has its own colors: Fill Shape: solid or gradient fill, Drop Shadow/Inner Shadow colors, Inner and Outer glow colors and Stroke: solid/gradient
The most simple way to adjust object(s) colors is to adjust its hue/saturation/lightness via the Edit Toolbar's Colors menu.
After you Select an object(s) (you can for example select all objects in the template you like to customize), click the Colors menu, then drag hue(color), saturation(colorfulness) or lightness sliders to adjust visual appearance of object(s) as desired.
As it is the most simple it is also the most inaccurate way to setup colors
After you Select an object(s) you wish to apply colors to. Click one of Styles Library items to apply color styles to this object(s).
By this way you also set all styles of object(s) to the one you selected