Q: How do I switch a drawing I created using one scale to a different scale?
A: Use the DIMSCALE system variable to set the scale of the drawing. Make sure it is set properly.
Run the Coordinate Drawings and Database command.
Ribbon: DM->Utilities-> 
->Coordinate Drawings and Database
Pulldown Menu: DM->Utilities->Coordinate Drawings and Database
This command will update all devices, text, and symbols inserted by Design Master on your drawing to the new scale.
Schedules will need to be updated separately using their respective commands to use the new scale.
Text and symbols inserted using standard CAD commands will need to be updated manually to the new scale.
If you are using Design Master HVAC, you will also need to redraw the ductwork using the DM HVAC->2D Drafting->Draw Double Line command to update the size of the ductwork labels.
Ribbon: DM HVAC->Ducts->Draw Double Line (Branch/Window)
Pulldown Menu: DM HVAC->2D Drawing->Draw Double Line (Branch/Window)