There is only one Model-Editor. It is the 'General Assembly'.
Click the Model name-tab to make the Model-Editor active.
Model in Model-Editor
In the Model-Editor, it is in-convenient [annoying] that Solids turn red [default colour] as you move your mouse over them.
To stop this happening, add a filter for an element you cannot see in the Model-Editor. E.g.:
The Solids will not turn red as you move your mouse above Solid elements.