I bought a Yamaha YPT-300 keyboard, and I am relearning the chords I learned 50 years ago at FL State University as a clarinet major. I can read and play music. It has always worried me whether I am using the correct fingers on my left hand for the bass part. I notice on the easy piano music pieces that the fingers are mostly not marked for Eine Kleine Nachtmusik, etc.. Should I forge ahead and try not to think about it? Thanks for your reply.

I think one should use whatever is most comfortable and easy for one to play. In fact, one doesn't really have to use the recommended fingerings at all (unless it's an etude, of course, otherwise it defeats the purpose of the lesson). Most pieces of music do not have fingerings anyway.