GROUPING AND LAYERING
Boxes can be layered; brought to the front or sent behind another, or grouped (uniting two or more images together). Grouping is helpful when placing multiple objects on more than one slide, such as a forward and backward button. By grouping them together, they can be applied to any slides, with the same alignment to each other (e.g., spacing, location, etc.) Another option is to put them on the Slide Master.
Under the Draw menu>Order