Need to change text color manually…

I’m using the ‘Membership 2’ plugin and the forms generated by its shortcodes have text that is too light to read on its already light background. I’d love to know how to change this awful text color to black.. If I need to edit a specific file, which one? etc. I did attempt to figure this out via the dev’s forum but it was less than helpful and I am not permitted to ask a question unless I register, and I have to fork out some dollars to do so.

Any help on this would be massively appreciated. Seriously.