Amazon IAM roles used to establish a trusted relationship between your AWS account and a third-party entity (also known as cross-account access roles) are using Multi-Factor Authentication (MFA) or external IDs to secure the access to your resources
1. Sign in to the AWS Management Console.
2. Navigate to IAM dashboard.
3. In the left navigation panel, choose Roles.
4. Click on the name (link) of the cross-account IAM role that you want to reconfigure.
5. On the Summary page, select the Trust relationships tab and click Edit trust relationship button to initiate the update process.
6. On the Edit trust relationship page, add one of the following blocks to the existing policy:<ol style=list-style-type: lower-alpha