How to set default view in Activity partylist look up for required/optional attendees look up

Hello,

I am working on MS CRM 2015 application . Need to implement the below functionality in Appointment using Javascript :

1. User should select the account record from regarding field look up in Appointment

2. In Required/Optional Attendees look up , default view should be set to Contact instead of Account .

3. The contact view should bring only associated contact for the account which was selected in regarding field look up