The correct modeling direction should be defined in a new Signavio workspace before any process models are created. This definition should be consistent with the workflow engine.
The standard modeling direction can be changed in the Signavio Process Editor, consider, however, that all existing models modeled with another modeling direction as default will display errors and need to be altered. It is possible to choose ‘horizontal’ or ‘vertical’ as modeling direction in the Editor. A consequent compliance in the chosen direction is absolutely necessary.