Problem Statement

CSV spreadsheet files are suitable for storing tabular data in a relatively portable way. The CSV format is flexible but somewhat ill-defined.
For present purposes, authors may assume that the data fields contain no commas, backslashes, or quotation marks.

Read a CSV file, change some values and save the changes back to a file. For this task we will use the following CSV file: Suggestions

Let's start with the solution:

Loop, Read, Data.csv
{
    i := A_Index
    Loop, Parse, A_LoopReadLine, CSV
        Output .= (i=A_Index && i!=1 ? A_LoopField**2 : A_LoopField) (A_Index=5 ? "`n" : ",")
}
FileAppend, %Output%, NewData.csv