That's the problem right there. Master/slave doesn't exist in DMX. You can group fixtures together to behave pretty much like that though.
You don't use Master/Slave mode on MyDMX. You set them for DMX operation. Check your DIP switch positions and power cycle your fixtures once you've assigned your addresses. MyDMX has a "DIP SWITCH" cheat sheet to show you how to set them for the locations you want to set them.
Not 100% certain, but unles the fixture has a DMNX setting for random rotation, the 3D Visualizer isn't going to animate that.