interesting.
so if you do it yourself, you don't need to do a factory reset if you want to change the main account?
what is a factory reset? can you do it yourself, or you actually have to send it to the factory to do it ?
Not exactly. I think what people are saying is "account#1" is the account you enter when there are no existing accounts. then you can also add other users. they are saying if you want to change that "account#1" you will need to factory reset. factory reset is just a "restore this device to a new state" option that exists in the menus, you can choose it - it will "wipe" your device, and allow you to start over. (if you do you will lose any data, like pictures and app settings, that you dont have backed up to a location off of the device.)
pretty sure they require the factory wipe is to prevent: one user with a lot of apps signs on to the device, downloads the apps, then switches the account to another person thus "giving" them the apps
On the very FIRST time you power up the device, you go through a setup wizard, where you are given the option to sign into your Google Account (you don't actually *have* to...but for the sake of argument, we'll assume you did, since you need to do that to access any Google services). When you buy a Nexus product from Google, they give you the option to have them complete this setup wizard for you, so your device is already setup for you out of the box. Regardless of whether you have Google do this or you do it yourself, that account that you setup is the PRIMARY account on the device. Once that's done, you can add and remove secondary accounts if you wish, however the only way to remove the primary account is to do a factory reset.
The factory reset clears all data (apps, settings, etc) from the device and re-enables the setup wizard. On a non-rooted device with stock recovery partition, you can do this directly from the settings menu (I forget exact location and don't have my tab in front of me right now); if you are rooted w/ custom recovery partition, you will want to boot to Recovery and do it from there. I emphasize that ALL data will be cleared from the device -- it will literally put the device back the same state it was out of the box (although it does not "uninstall" OS updates). This is, as far as I know, the only way to change the PRIMARY account on a device.
Usually, a factory reset preformed from a custom recovery will not delete your personal files, such as pictures and media (anything under the "/sdcard" directory) -- but you should always backup just to be safe.
Personally, I don't advise choosing the option to have Google do it. For one, it's quite easy to setup yourself -- it takes only a minute or two -- and second, you know your device hasn't been "handled" by Google employees prior to shipping.