Kindles are "kindle eInk readers" which are pretty dumb book reading devices. Having said that they are FANTASTIC dumb book reading devices. (Hey I loved Sony and Kobo - have had countless Kindle ereaders and love them the best!)
Generic web advice is generally about "amazon devices" which is nearly always about the Fire tablet device. Most information and advice on the FIRE is useless for the Kindle and vice versa.
At the top of this page is a great fast track "!Identify your device" and this feeds you to the specific answers to 99% of your specific questions for your device.
I think the Paperwhite needs to use the RESTORE FACTORY DEFAULTS option to reset the device if you forget the password.