How can I update cell value of a data table?

if Records is your DataTable do this:

Records.Rows[i][j] = value;

this does not answer the whole question but shows you how to set a value in a DataTable "cell".

you are using the ItemArray which is not needed because once you have the right Row you can simply access its columns withh []

you can elaborate more and find out the final solution based on this hint.

If you use Records.Rows[0].ItemArray[2] = value this won't work, but if you use Records.Rows[0][2] = value this works perfectly.