Locking form fields

I am creating a quote form that my sales team can fill in the form fields and send to their customers for signature. I would like the form fields to be locked after my sales team fills it out, so the customer cannot inadvertently change the price or details. However my sales team does not have Acrobat. I am testing putting in a digital signature field that they are to sign after filling out the form. I said to lock then all but the customer signature. I saved as reader extended. I am testing the form and she said it is asking for a password, which I did not assign.

How would I work locking the form fields in this scenario?