Restrict users from editing the date field on an Invoice

To restrict users from editing the Date field and to make sure that the actual creation date is the same with the Date field, follow the steps below:

1.    Navigate to Setup > Customization > Transaction Forms.

2.    Select the preferred Invoice Form.

3.    Hit Edit or Customize whichever is more applicable.

4.    Go to Screen Fields subtab then go to Main sublist.

5.    Set the Display Type of the Date field to Disabled.