Attaching ServiceAccount for Medusa Backup in S3


I am trying to create medusa backup and store the data in S3. My cluster is hosted on AWS EKS, and the node-group or the EC2 instance already has a default IAM role attached to it which should not be modified. I have created a custom IAM role similar to what was mentioned in the document and attached it to my bucket. I also created a ServiceAccount to attach this role to the MedusaBackUpJob. The medusa pod however is still reading the default IAM role that is attached to the instance. Is there a way in which we can have these custom roles used to backup data in S3?