Kafka cluster configuration file jaas-kafka-server.conf

In one our configuration file jaas-kafka-server.conf we have passwords which should be change:

cat jaas-kafka-server.conf
KafkaServer {
    org.apache.kafka.common.security.scram.ScramLoginModule required
    username="admin"
    password="kafka123";
};

Client {
   org.apache.zookeeper.server.auth.DigestLoginModule required
   username="admin"
   password="kafka123";
};

What should be the procedure for changing such passwords to more secure? What is the impact of such operation on the Kafka cluster and applications which are connecting with Kafka?