If you made an error when you first logged in and selected the collections within your model, you can drop that model and re-enroll.
Simple go to the upper right corner, where it says 'Me' and click the down arrow. From there, select 'Settings'.
Once in your settings, you will see the model(s) you are enrolled in. If you select 'Actions', you can drop that model in order to re-enroll with the specified collections you prefer.
The next time you login, you will be prompted to select a model, or you can click '+ Enroll in New Portfolio' and update it now.