In your Browser, enter the IP address of your wifi router (IP address is written on the manual or indicated on a sticker of the device but usually 192.168.1.1). Enter username and password when prompted (usually admin, admin).
If the username and password are correct then it will get you to the Dashboard of your router where you could change the settings including the password.
The upload speed is dependent on the network (and your subscription) and it would be best to call customer service for this. Sadly, there is no assurance that you can be able to achieve this on a constant basis UNLESS you subscribe for a business line (subscriptions are a lot higher than consumer plans).