Hey PeteCC,

Since I can't actually see your fingers, I'll take a guess.

You *might* be over-extending your forearm, putting your thumb too far behind the neck, and arching those fingers too much. But I can't be certain!

While we are often told as beginners to keep the thumb way behind the neck, it's really not a practical thing in regular playing. It all depends on what you are playing. Watch any famous guitarist and they almost always move their thumb all over the place, behind, on top, etc.

Also, I am not totally sure what you mean by "flattening." If you're trying to go to A Minor from G Major there shouldn't really be any flattening or barring happening.

That said, G Major is an oddball chord in the open position, and is hard to get at first since you're playing such extremes (high and low strings far apart).

Feel free to post a picture / video of the problem or email them to me to check out: carl@guitartricks.com.

-Carl.