I just realized that the new Autocad architecture 2011 comes with a new plotting interface, I can´t edit my layers thickness, it is so different, please HELP!!! I attach an image of the interface. It is urgent Thanks!
You are using STB to print according to your attached image. If you would like to be able to adjust lineweights by layer, you need to use CTBs to print. In your dwg, use CONVERTPSTYLES to switch to CTB.
You can set lineweights "by layer" with STBs just as easily as you can with CTBs. If I am translating correctly, all of the plot styles defined in the posted image are set to use the object's lineweight. If all of the main objects are set to a lineweight of ByLayer, then the main objects will plot with the lineweight assigned to the layer.
Nested objects and linework controlled by display settings are a bit more complex, but that holds true for CTB-based plot styles as well as STB-based.