How do I get the value of previous category?

Hello,

I'm trying to get the value of a previous category for my personal finance sheet.
I have different accounts and I want to have both old balance and new balance show that is maintained under the same table.
1.png

Bascially, I would need the current 'old balance' to show previous 'new balance' in the same 'account'.
To simplify this question, here is an example.
3.PNG

As you can see, D7 shows C2.

I was trying to use Index (New Balance Array, Row # of previous category).
What I'm having trouble is getting the row# of the previous category.
I was using COUNTIF (START OF CATEGORY : CURRENT CATEGORY, CATEGORY) to get the # of row that the previous category is within the category.
Now, I am stuck on using this number to get the row number in overall.