Is there a way to easly check if I did updates to the theme?

Hi, Unfortunatley, I can't remember if I updated the theme files. I know I added some code via the CSS, but I don't remember if I updated the files (I have different sites which use catch responsive (pro)). In the past I did things to the files, buit that was with a different theme, so... I'm just not sure. So, is there a way to easly check if I did updates to the theme? I could copy them all to Word and do a text comparison per file, but that seems a lot of work. And I don't understand how child themes work. If I update the parent, am I running the newest version?