Do I have to submit a copy of my credentials for verification?

The credential filter used in jobs is based only on whether you have declared your credentials. Verifying your credentials benefits your profile and you, and is an added assurance to potential clients that you are a qualified professional. 

Note: if you declare a credential, you may be asked by the site to verify the existence of that credential in your name. If you are unable to verify a credential you have declared, it may be removed from your profile.