This is the current layout of my data fields on my Garmin Edge 530. Is there a way to move the large HR data field in the place of the two smaller data fields at the top? I've tried swapping fields, but the large tile remains where it is.

It's not hard, look at the examples, select one and just modify it I find is the easiest way. Also, everytime you do something, no matter how small, get into the habit of doing a "Save", the app does have a bug in it that causes it to crash and you lose your work. But, the app starts up very fast and it will be where you left off.