Changing voices in Note Entry Mode

Sorry, I seem to be posting quite a few requests for help.

I'm writing for classical guitar so I'm always using multiple voices on the same stave and I'm having problems getting it to work properly. The manual says :
. First start by entering the top voice (all the up-stem notes).
· Now select the first note to move your cursor back to the beginning of the line.
· Click on "Voice 2" button and start entering the bottom voice (all the down-stem notes).

Entering the top voice is no problem but how do I "select the first note"? If I position the cursor on it and click MS enters another note. What I've been doing is selecting the next voice number then using the left arrow key to position myself at the beginning of the bar then selecting the note value. However, when I enter the note, whether from the keyboard or the mouse it seems to revert to voice 1 and place the note in the next empty bar. If I select the new voice again and then use the left arrow key to position myself at the beginning of the bar I'm trying enter it seems to work OK. I presume I'm just misunderstanding something. Can anybody put me right?

Thanks