You can adjust the size, position and rotation of a selected object using your mouse on the 3D workspace.
To get started select an object on the AR Contentpanel on the left.
You can use the tools panel on the 3D Workspace to switch between moving, rotating and changing the size of your object.
For example, to adjust the position of your object select Move on the tools panel and drag your object using red, green and blue arrows to move it along one the axis.
You can also use the Appearance tab of the Properties panel on the right side of the to adjust the scale, position and rotation of your augmented reality content using the sliders or entering exact numbers.