I am still mystified by your instructions. Now that I'm seeing both you and the original author are saying the same thing, it is now clear to me that y'all must be seeing something I cannot see.

You gave two sets of instructions. Step 5 in the first set of instructions (Manually type in the amount you want to refund in the Amount field, then Submit.) and step 6 in the second set of instructions (Type in the amount you want to refund, then Submit.) are not things I can replicate on my end.

I have shared a screenshot of where I get to when I follow your instructions. From this screen, where is it that I type an amount?