Hi Ursula,
I’m sorry that you’re not happy with the tooltip formatting…you can change the height and styling of the tooltip by adding some CSS to the Additional CSS area under Appearance > Customize (if you have one) or to the style.css file of your child theme.
To change the content, you would need to do a template override. Our themer’s guide has instructions on this, and the template can be found at wp-content/plugins/the-events-calendar/src/views/month/tooltip.php.
We are a bit limited in the amount of support that we can provide for customizations, but if you get stuck or have any questions, please let me know – I’ll be happy to point you in the right direction!
Thanks,
Jennifer