Correct Method of Keeping Fingers?

Hello Claire,
It's difficult to answer your question without knowing more about what is correct or incorrect in your way of playing. For instance, you might have learnt pieces with wrong fingering, which gives you a limit in terms of evenness or in the tempo you may reach without slips. In such a case, you are better practicing a new, correct fingering, starting at a low tempo and rising this tempo steadily. It is boring, but it works if you are patient enough. But maybe it is your global approach of the piano which should be changed, according to a teacher ? As your position, the way you put the hands on the keyboard, how you use or not the arm weight, how you shape your hand (curved or flat) etc. What can be said is that old habits are the most difficult to change. But it is possible with patience and rigor... First you should find a teacher that you trust as a valuable coach. Then you have to follow his advices as much as possible... Good luck !