Follow along with the video below to see how to install our site as a web app on your home screen.
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The easiest way to change accounts is to go to Settings>Applications>Gmail and clear all data. I also did it for gTalk and all other Google related apps. This created a notification that I needed to redo the setup wizard with a link in the notification to start it. This fixed everything and didn't have to worry about a hard-reset.
A little Googling found this: