How to select and change value of table cell with jQuery?

Answer 1

$("td:contains('c')").html("new");

or, more precisely $("#table_headers td:contains('c')").html("new");

and maybe for reuse you could create a function to call

function ReplaceCellContent(find, replace)
{
    $("#table_headers td:contains('" + find + "')").html(replace);
}