Can I change job with L 1 A blanket petition visa?

Your L-1A petitioning employer is not required to petition for you to receive a green card. The decision about whether to initiate the green card process is solely within the discretion of the employer.  You cannot simply transfer your L-1A status to a new employer. L-1A status is tied to employment with a specific employer. A subsequent employer would need to seek either a nonimmigrant or immigrant visa on your behalf for you to leave your current employer.  You can read more about L-1A blanket petitions at http://myattorneyusa.com/l-blanket-petitions.