From the Menu Build > Configuration Manager, you can edit all configuration for the solution. You can have a solution named as you want (when selection "new" in Active solution platform, you can write the name you want) and assign wich configuration you want for each project (Win32, x86, and so on ...)
What you see in VS2012's toolbar, it's the active solution platform. If you want it to be named "My platform for x86", you can do it;)