You can customize the fields you want to see when chatting with people and what is required to fill out when creating New Lead, New Contact, New Account, New Activity, New Task, New Case.
Click on your user on the Tuvis' panel and then click on 'Edit Layouts'
Select the relevant layout you want to modify on 'Select Layout' and choose what field you would like to add on 'Add New Field' or delete the ones you would like to remove by clicking on the trash icon.
Display: Lead, Contact and Account
Create: New Lead, New Contact, New Account, New Activity, New Task, New Case