Just wondering if the system for this should be upgraded?

What has trigered me to think about this as the events that happened today:

Dad was complaining that the internet was being slow, So I checked if we had gone onto dial-up, just arriving home from being out for the afternoon, I used his computer to check, once I had realised that we hadnt, I reset the router and everything was all fine. BUT I left the window open.

Now because I know all the passwords for the network, and Dad knows none of them, occaisionally he asks for them, I tell him them and change them 5 minutes later :P well he decided that he wanted the broadband one, so instead of asking me for it, he changed it on our accounts page that I had left open on his laptop.

(he told me he had done this 2 hours later, at which time I had been on hold with xnet for 20minutes before getting called to dinner,(when he told me he had done it)  then I waited another 2 hours before finally coming ot the realisation that dad had changed the password, which meant it needed to be changed on the router. (one of those smart moments) :D

But does the system need to ask you for your password when you change it? rather than asking you for it when you log in and then you can change it, what if you left it open in a public place?

I realise that as the account holder you have to ensure that you log out and then close the window once you have finished, but should this be added as an extra security measure?