All the repositories/ppas that are considered are either in /etc/apt/sources.list and any files in /etc/apt/sources.list.d. You can remove the daily-build ppa and make sure the stable-build ppa is still there.
Any change in the sources must be followed by executing "sudo apt-get update" in order to take effect...
if you use
apt-cache policy <packagename>
you can check all the candidates for a particular package.
I believe the stable ppa you are looking for is ppa:chromium-daily/stable (https://launchpad.net/~chromium-daily/+archive/stable)
The link has instructions how to add it to your sources.