I have the same kit. It is a few years since I bought it so cannot remeber how I set the handsets up, but they hand over with the current speed on my layout. Maybe this bump will find someone who knows.
I had a special pair of glasses made with , I think, +2 dioptres above my normal reading prescription. I tried a few pairs at a newsagents before giing to the optician (may be frowned upon now).