Edit Title Padding,

I have the pro (personal) version of the video gallery but I am unable to edit the CSS for styling. I add it to the child theme but nothing changes. I’ve used child themes before to do this but it is not working with this plugin. I want to add padding to the titles as they do not look right on the edge. How can I do this?

https://ww.wp.xz.cn/plugins/gallery-video/