I'm an Android user so I'm not sure what the situation is for IOS but, on Android at least, you can't change download location. This is really annoying as I have to constantly move files after downloading. Please fix this.
(Note: similar ideas have been merged into this thread)
This should be a basic feature in any browser, ideally in the browser's settling UI. The fact that you can't even do this in about:config is mind boggling.