To do this for all controls, go to Tools|Options|Keyboard tab and set the
desired setting under "Behavior entering field". To do this for just one
control, in the Click or Enter event of the control try something like:
Me.ActiveControl.SelStart = 0
If you do this in the Enter event, when you tab into the control it will do
what you want. If you click into the control, the cursor will go where
you've clicked. If you do it in the click event, the cursor will go where
you've clicked when the mouse button is down, but will jump to the start of
the field text when you release the mouse button. You may need to place the
code in both locations.