I assume by "check" you mean "check on" rather than "enable," as these boxes must be
unchecked for the Insert key to toggle between Insert and Overtype and for Insert to be the current setting. Note that, when "Use the INS key for paste" is
not checked, then toggling the Insert key has the same effect as checking/clearing the "Overtype mode" box (which reflects the current state of the Insert key).
As Doug points out, the current setting is also represented by the appearance of the OVR button on the status bar, though it is necessary to
double-click this to change the state.
