in the
dgvDetails_SelectedIndexChanged
event set the button's text to "Update".
btn_mysaveupdatebutton.Text = "Update";
When the button is pressed you do:
private void btn_mysaveupdatebutton_Clicked(...){
btn_mysaveupdatebutton.Text = "Save";
}
You're talking about a form, but the tags of the questions mention Asp.Net. There's a huge difference, if the response does not solve the problem, please update your question.