Here's a Python program that takes user input for creating EBS snapshots, initializing volumes, and changing encryption keys for EBS volumes using the AWS SDK (Boto3).

import boto3

# Initialize AWS clients
ec2 = boto3.client('ec2')

def create_snapshot():
    # Take user input for the volume ID and description
    volume_id = input("Enter the EBS volume ID for snapshot creation: ")
    description = input("Enter a description for the snapshot: ")

    # Create an EBS snapshot
    snapshot = ec2.create_snapshot(
        VolumeId=volume_id,
        Description=description
    )

    print(f"Snapshot {snapshot['SnapshotId']} created.")

def initialize_volume():
    # Take user input for the volume ID and description
    volume_id = input("Enter the EBS volume ID for initialization: ")
    description = input("Enter a description for the volume initialization: ")

    # Initialize the EBS volume from a snapshot
    response = ec2.create_volume(
        AvailabilityZone='us-east-1a',  # Replace with your desired availability zone
        SnapshotId='your-snapshot-id',  # Replace with the snapshot ID to initialize from
        Description=description
    )

    print(f"Volume {response['VolumeId']} initialized from snapshot.")

def change_encryption_key():
    # Take user input for the volume ID and new KMS encryption key ARN
    volume_id = input("Enter the EBS volume ID for encryption key change: ")
    kms_key_arn = input("Enter the new KMS encryption key ARN: ")

    # Modify the volume's encryption key
    ec2.modify_volume(
        VolumeId=volume_id,
        KmsKeyId=kms_key_arn
    )

    print(f"Encryption key for volume {volume_id} changed to {kms_key_arn}.")

if __name__ == '__main__':
    while True:
        print("EBS Volume Management Menu:")
        print("1. Create Snapshot")
        print("2. Initialize Volume from Snapshot")
        print("3. Change Encryption Key")
        print("4. Exit")
        choice = input("Select an option (1/2/3/4): ")

        if choice == '1':
            create_snapshot()
        elif choice == '2':
            initialize_volume()
        elif choice == '3':
            change_encryption_key()
        elif choice == '4':
            break
        else:
            print("Invalid choice. Please select a valid option.")

Before running this program, make sure to configure your AWS credentials, region, and customize the AvailabilityZone in the initialize_volume function. You'll also need to replace `your-snapshot-id` with the actual snapshot ID you want to use for volume initialization.
This program provides a simple command-line menu for creating snapshots, initializing volumes from snapshots, and changing encryption keys for EBS volumes. It demonstrates how to take user input and use Boto3 to interact with AWS EBS resources.