ProjectWise Forms

We create a form and all is will. We apply the workflow and all is well for all status values with the exception that when the issue is created, we cannot find a way to lock specific fields on the form. All fields are active. Once the form instance is created, the workflow handles locking. The form has a toggle for is the issue valid and was it back checked? I don't want these fields to be edited until it gets to the reviewer? How can I lock certain fields when  the form is first instantiated?