I'm having a hell of a time tracking where i can change/update the default user profile photo/thumbnail folder location. I keep reading and have tested that you can create a new volume for assets. My interest is is being able to locate and change the default folder location. Any advice?
In Craft 3 the place that users photos get stored in are proper Asset Volumes, meaning they can be stored in a folder on the local file system, or on S3, Google Cloud, or any other place that a plugin provides a Volume for.
Once you create a Volume for user photos, go to Settings->Users->Settings in the Control Panel and you can choose that Volume under the "User Photo Volume" settings.
I am only able to speak about Craft 2x, as I am not familiar at all with how Craft 3 handles profile images.
Here is where Craft 2x stores any uploaded profile image:
It is kind of a special asset source that isn't accessible like you would find an asset field that you create is. You can render the image, but as far as I know, you are not able to change it's location.
Hope this helps!