I am creating a new master shape and would like the text (when user pressesto be placed above the shape and not in the middle. How can that be configured?
What this means is you want to control the Text Block of the shape. The good news is that you have a lot of control over this in Visio.
First, to this you'll need to use the Text Block tool (highlighted below) on the Home tab of the Ribbon to get started.
The instructions are for using the tool are here at the online documentation for Visio 2010.
Also, to get the text block working perfectly when shapes are resized you'll need to set the Text Transform section in the ShapeSheet to achieve your desired outcome. This section allows you to control the size and positioning of the text block.
The Text Transform section is shown below