By default, the assignment icon is placed at the top left corner of objects to which one or more models have been assigned.
If you assign a database its own assignment icon, it is placed at the bottom right corner of objects.
It is shown for the current model if you specify in the model properties (Representation tab) that assignment icons are to be displayed. For all new models, you can specify this setting on the Representation options page (ARIS > Options > Model > For new models).