When you create custom graphs, you can have one or more of them displayed during simulation. If you do this, when you start the simulation you will see a custom graph, and the values will fill in as the simulation progresses. You can move and resize the graphs during the simulation, although your system might respond somewhat sluggishly.
If you are simulating with the Sketch Editor open and you have one or more Work-in-Progress graphs in Output Objects on the current view Vensim will write to these graphs, but not open any additional Work-in-Progress graphs.
If you ask for more than one graph to be displayed during a simulation, the graphs will open on top of one another. You can move them around, and then use the Rec Coord button on the Graphs tab of the Control Palen to have them come up where you positioned them the next time you simulate the model.