can AWS elastic beanstalk be configured or moved to another AZ

I recently deployed a ruby on rails app on elastic beanstalk.

 eb init 
 eb create nameofthebeanstalkapp
 eb deploy

Basically this will initialize the region and some other settings but not the AZ location.

For example, I selected North Virgin, but it didnt ask the AZ location. So it creates it in us-east-1c. I would prefer it to be in us-east-1b where my RDS service is located.

How do I change over my EC2 instance to us-east-1b from us-east-1c ?

Thanks.