New Amazon EBS volumes aren’t encrypted by default. However, there is a setting in the Amazon Elastic Compute Cloud (Amazon EC2) console that turns on encryption by default for all new Amazon EBS volumes and snapshot copies created within a specified Region.
Steps – >
1) Open the Amazon EC2 console.
2) Select the Region from the drop-down menu.
3) On the EC2 Dashboard, under Account Attributes, select Settings.
4) Under EBS Storage, select Always encrypt new EBS volumes.
5) Select Change the default key and choose any of your keys (default/CMKs) as the
Default encryption key.
6) Select Save Settings.
7) Repeat these steps for other Regions as needed.