How to update values in gridview

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C#

Windows

forms

Hi guys. I would like to know how to implement the below scenario.

I have 5 buttons loaded dynamically during form load. Each button has Amount of Rs.100.

I click Button 1 and redeem 50 Rs. and I click Button 2 and redeem 10 Rs.
in UI it will shown as
Button 1 = 50
Button 2 = 10 in gridview

Again I use the same Button 1 to redeem 20Rs. Now UI should show
Button 1 = 70
Button 2 = 10
How to achieve this updation of Button 1? .

What I have tried:

this.dataGridView1.Rows.Add(ButtonName, "$" + Amount.ToString("F"));

I used this . But it is adding new rows even when i update the same button.