Re-installing Big Sur 11.1: What is safest/best way? And required to be logged in to Apple ID?
Questions regarding re-installing Big Sur:
Device: 2015 MacBook 12” Retina. Current OS: Big Sur 11.1
I bought this MacBook secondhand from a local interior-design company that was downsizing. They kindly had wiped the drive and installed Big Sur 11.1 on it before selling it. When I bought it, they said it would be wise for me to re-install Big Sur 11.1 so that I could start completely fresh, since they had created the main User account to be called “Sell” and also their old company AppleID was still the default active AppleID account on the computer, even though it was a new fresh install. My questions are:
• It is indeed necessary (or wise) to re-install Big Sur, since I don’t really know for sure what programs they may have installed on it or how they may have fiddled with the OS before selling it to me?
• In earlier versions of OS X that I was familiar with, it was not possible to change the “short User name,” once it has been created. Is that still true in Big Sur? Or would I actually be able to fundamentally rename the “Sell” admin account. I suspect the answer is "No,” which is my main reason for re-installing the OS.
• If I re-install, will I be able to wipe away the original pre-existing admin User account completely, and in its place create a whole new top-level Admin account called whatever I choose?
• If I can indeed completely remove the old User account during re-installation, then (in theory) what would happen to any user-created files that previously had been stored in HD>Users>[old-account-name]? In reality I still have not created (or migrated or transferred) any user-created files to this MacBook, so I’m not in danger of losing anything — I’m just curious about what would happen to a User’s files if that User’s entire account was wiped out during re-installation.
• In order to re-install Big Sur 11.1, must I be logged in to an AppleID account? This wasn’t the case in previous versions of OS X that I’m familiar with, but with Apple’s new software downloading protocols (that I’m still learning about), I suspect that perhaps it might be necessary to be logged in to re-install the OS. And if I indeed must be logged in to an AppleID, will that AppleID be the default account to which I will still be logged in after installation? Will I be able to later log out and re-log in to a different AppleID account? Will the name associated with the AppleID account I used for re-installation in be somehow forever associated with this installation?
• To initiate the re-install, should I first shut down the MacBook completely, and then re-boot in “Safe Mode,” and start the re-installation from within Safe Mode? How is that (rebooting in Safe Mode, and then reinstalling from Safe Mode) done in Big Sur?
Any advice — even answering only one of my questions — would be greatly appreciated. Thanks.