Do I have the legal option to sign the paper doc of the Arbritration Agreement?

Good day,
I am an employee of Ross Stores.
A few days ago, approx. Friday March 22, 13, I was approached by the store manager and presented with the company's Dispute Resolution Agreement which states that I agree to settling disputes by arbitration rather than via the public court system. The document does not indicate that it is mandatory that I should sign this document in order to maintain continued employment at Ross Stores. The last paragraph states that the agreement is wholly mutual between Ross Stores and myself . However, the store manager, Paul-Brian De Leon, verbally conveyed to me that the condition of continued employment for all Ross employees was the required acknowlegement of the Dispute Resolution Agreement by clicking the check box on the computer screen, and not signing the paper document he also gave me.
The Dispute Resolution Agreement document does not state that signing the document is mandatory to maintain empoyment. If I sign the document with my signature, I want to be able to add an addendum stating: "I am being told that signing this agreement is manatory and a condition of my continued employment ."
But the computer method does not offer that option. Therefore, I want to sign the paper document of the Dispute Resolution Agreement with my addendum statement and it can be scanned into my file, and I can retain a copy of it for my own records.
I have questions about this whole process. I have been working for Ross Stores for over 15 years as a full time employee without having signed a mandatory arbitration agreement and now suddenly I am being required to sign one.

Looking forward to your meeting on the phone. Best time to call is about 9:30 am to 11:00 am.

Telephone 1 408 379 4961

Thank you,
Elizabeth Anderson