Fields can be in the state of read-only to all users. Only Portal Admins can edit this field.
1. Go to Templates and Revise the template you want to edit.
2. Select the field you want to edit. Choose the workflow field or "Read only". You cannot have multiple workflows to a field. Click Save.
3. The field on a project is read only for all users and you will see the read only icon when you mouse over it.
4. Portal admins who need to edit this field can edit it on the web app only. Click on the read only icon (eye) and this will make the field editable.