Changing the default sqlite username and password

This is probably a really dumb question - when using sqlite as the database with this suggested command from the readme:

docker run -v /opt/wallabag/data:/var/www/wallabag/data -v /opt/wallabag/images:/var/www/wallabag/web/assets/images -p 80:80 wallabag/wallabag

how do I change the default username and password? (sorry for asking a newbie question)