I'm not sure if this was ever asked before but say I wanted to change the password to my Live account linked to my phone, how can I update that info on my phone without a hard reset?
Just change the Live ID password on a PC.
Go to your Windows Phone, acconts and emails
Long press on the Windows Live account and tap Sync.
It will notify you to tap and correct sync error.
Tap and enter your new passowrd there....DONE!
Hope it helps.