After selecting a SketchUp object in the drawing area, you can edit it by changing the properties in the green properties box:

• Even Scaling: Check this box to ensure that models retain their proportions when scaled.
• Width, Depth, Height: Set an exact size on the imported object.
• Reset Scale: Reset the model back to its original size.
• Elevation: Decide how high above the floor the object should be placed.
  
  You can also use the PgUp and PgDn keys to raise and lower the symbol.
• Restore materials: Revert any new materials from the Material Explorer that you have painted on the symbol.
  
  Read here on how to apply Materials: Using the Material Explorer