I need help
I understand that the bottom button saves the order before moving on to purchase,
but I'm having trouble with orders with unfinished purchases in admin.
But what makes the top button for settings, and what affects the change.
What preferences do you prefer?
If you are receiving a lot of unfinished orders that indicates the order was either not fulfilled (Paypal should log payment errors as a hidden comment in later versions). Or something went wrong during the route back to the store after a payment was fulfilled (this is why you can save orders first so you don't lose them).

Reserve, Capture, and Authorize are terms some providers roll out as 2 in 1 or can differ or be named differently. So I would recommend you send ePay the question what really goes on when you perform a capture. My spontaneous guess is the amount is immediately reserved and authorized for withdraw (what might be most commnly called Authorize). But they should be able to respond to this question properly for you.