The PlaceMaker height settings (including level height) for buildings and trees are only considered by PlaceMaker where the OpenStreetMap data does not provide specific height information.
If the information is available, PlaceMaker will use the 'height' tag for the imported object so that it will be created at the correct height. But sometimes, this tag is not available and PlaceMaker must use the default settings instead.
If you want to ‘fix’ the height of a specific building or tree, the best way would be to use the online OSM editor to add the correct ‘height’ tag to the object.
You can also use the SketchUp tools like push/pull or scale to modify the height. But in this case, if you try to import the objects again, the height will be reverted to the original value since the OSM data was not actually changed.