By default, textbox controls work in insert mode, where each new character never overwrites existing ones. If you wish to implement overwrite mode you can take advantage of the fact that characters pressed by the user replace the currently selected text, if any.

You need to declare a form-level variable that holds the current mode, and modify the KeyPress event of the text box control. You also need to add some code to the KeyDown event procedure, in order to trap the INS key and pass from insert mode to overwrite mode and vice versa:

' form level variableDim overwriteMode As BooleanSub Text1_KeyPress (KeyAscii As Integer)    If overwriteMode And KeyAscii >= 32 And Text1.SelLength = 0 Then        ' we are in overwrite mode, the user hasn't pressed a        ' control key and there's no text currently highlighted        If Mid$(Text1.Text, Text1.SelStart + 1, 1) <> vbCr Then            ' we are not at the end of the current line of text            ' select the next character, so that it will be replaced by            ' key typed by the end user            Text1.SelLength = 1        End If    End IfEnd SubSub Text1_KeyDown (KeyCode As Integer, Shift As Integer)    If KeyCode = 45 And Shift = 0 Then        overwriteMode = Not overwriteMode    End IfEnd Sub