Change the dock orientation
In the dock panel, click a child element to select it.
Under Layout in the Properties panel, select a Dock value from the list (Left, Top, Right, or Bottom).
If you drag a child element of a dock panel on the artboard, notice that a large four-way cursor shows the directions that you can dock the element. You can use this four-way cursor as an alternative way to change dock orientation. Simply drag the element over the direction arrow that you want. Notice that the direction arrow that you select becomes highlighted, to indicate that you can drop the element to dock it in that direction.