Yes, one way you can set the (default) value of a control is by using a property node.
To do so, right click on your control and select Create/Property node. Then right-click on the property node and set it to All write. Finally, left-click on the text "Visible" and select value. If now you wire e.g. 5 to this property node in the beginning of your program, the control will display the value 5 when the users see it for the first time.
Hope this helps. /Mikael