Hi James. Sorry to hear you had issues with the add-on.

As far as the scrollbar buttons go, currently Firefox only supports limited scrollbar customizations. That only includes colors and very limited width settings. As Firefox adds more features (which I hope they do), I will be able to add more functionality.

As for no visible changes being shown, it's important to note that there are some pages the add-on cannot make changes to. These mainly include internal browser pages (settings, etc.) and pages that are generated by other add-ons. For more information, see: https://github.com/WesleyBranton/Custom-Scrollbar/wiki/Pages-this-extension-cannot-modify

Sadly, the narrow scrollbars is easily the more common feedback I get. I hope that the Firefox developers allow more customization options in the near future.

Unfortunately, Firefox only supports very limited scrollbar customization at the moment. I hope that changes in the future so that I can add more functionality for Firefox users.