If you are trying to edit the start date or effective date of a patient's insurance record from the Patient Insurance screen and that date is grayed out or disabled, this is because you do not have the special privilege to do so. This requires a special privilege as changing the effective date can affect many claims that might already have been billed to another insurance. Normally, Front Desk personnel should end date the current insurance and enter a new one. 

You would need to ask your system administrator. 

The Privilege name that you would need is under Functional Area Group: Patient Chart, Functional Tab: PatientInfo and called "Insurance StartDate Edit"