After creating elastic beanstalk you can modify setting .
Follow these steps :
Step 1: Login in to your aws account.
Step2: Click on My Account and select AWS Management Console from right hand side.
Step3: Click on Elastic Beanstalk .
Step4: After creating select Configuration tab
Step 5: After clicking Configuration tab you will see:
- Software Configuration
- Updates and Deployments
Step6: You can select what ever you want to change and after that click on save button .
For example :
I want to increase my Memory Limit
->Click on Software Configuration
->Increase memory limit 256M to according your requirement like 512 M
-> After that clcik on apply button