How to update row in Excel using MS Form=>MS Flow=>Excel sheet

Question

I have a MS Flow setup like this:

Form has 1 question Flow triggers from that Form Flow has Update a row in an excel table

It all works fine as long as i manually type text in the "Key Value" field in the "Update a row" part of my flow - see pic.

However, I don't want to manually type text in the "Key Value" field. I want Flow to automatically know which row to update in the table based on the Form response.

I can find no examples of how to do this - if you have a working example please explain.

Should I even be using Form, or should I be using something else to get the answers and update a spreadsheet.

Tried to find examples, can't find.