Hey @nyawindler,
Thank you for reaching out to us for assistance. You can find the customize options by going to Twitter Feeds > Customize and Style tabs. Here you will see all the customization options for the feed. If you need further customization than the built-in options allow, you can inspect the elements of the page to see the multiple CSS class available and create your own CSS. You can then add your own CSS to the plugin in the Custom CSS section, which can be found by going to Twitter Feeds > Customize > Misc > Custom CSS.
Let me know if you need any further guidance.
Best regards.