Modify the default administrator password
You can modify the CouchDB admin password with these steps:
Stop your server.
$ sudo /opt/bitnami/ctlscript.sh stop couchdb
Edit your /opt/bitnami/couchdb/etc/local.ini configuration file, editing the respective admin password to what you want, in the [admin] section. For example:
admin = my_new_password
CouchDB will take care of hashing your password, so the only thing you need is to start your server again.
$ sudo /opt/bitnami/ctlscript.sh restart couchdb