Code An 'increase' Button To Prompt A User To Input A Rate By Which To Increase Select Prices In An Array?

I'm trying to code an 'increase' button to prompt a user to input a rate by which to increase select prices in an array.It should request the increased rate, then request a number from one to five, representing which price in the array to increase.Then, if 'increase' button is selected again and another number from one to five is chosen, then that element should be increased.It's working, but all the numbers in the array are changed. And, when I hit the increase button again, the array is repopulated below the first price increases instead of only replacing the designated price.

'declare 5 element array of prices
Dim prices() As Double = {12.2, 8.5, 12, 50, 2.4}
Dim rateIncrease As Decimal
Dim isConverted As Boolean

[code].....