Hi,
I assume you want to make changes to a mesh when re-opening PreView? If the mesh is an editable mesh, then there are a few things you can do, but it depends on what exactly what you want to do. To make something bigger, you can use the scale tool. If you can click the scale icon on the main toolbar and then drag the colored arms that appear on the selected object. For more precise scaling, you can also open the Transform dialog (Edit\Transform …) and enter the scale factors manually. Please give that a try and let us know if that worked for you.
Best,
Steve
Department of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of Utah