Click the appropriate icon in fields top right. The selected icon will be outlined in green, that icon will also appear on fields top left, and fields and associations for that model will appear.
To view multiple models:
1.
Click the most important model first (this is the model whose fields you will see), then
2.
Ctrl+click on any other models you want to also include.
Icons only appear for NEs that in fact exist in one or more object model.
