How to stop: Firefox site, Chuck Shumer website & 1800flowers .com as I begin to enter my gmail address, it autofills including my full home address.

I thought Shumer's site had some secret government way of knowing it was my home address, but then repeated on the flower ordering site and on this support Mozilla site. Asks for your email account, begin to enter it, and it autocompletes including my home address, city, zip state, before I offer to enter that info. This is an invasion of my privacy. It's like when you call someone on your phone and they already have your phone number on their caller id, but in this case, includes your actual residence address. How to turn that off would be a very helpful bit of info, and searching it online only gives results that don't understand the question at all.