Well I think you exasperated your settings to a point they don't work.
You have max memory of 128M
But you have set limits of 500M
You need to set them to some realistic size with what you have to work with.
You were able to change the
Maximum Execution Time to like 1500 seconds. That is 25 minutes.
You really think somebody is going to wait 25 minutes to upload.
Also
I see a concern that you said:
When I attempt to access the phpinfo link, I get the message: "You must have the proper permission to access this area." and then it returns me to the forums.
What does that mean if you are using phpinfo in the UBB control panel.?
Someway somehow your admin account does not have proper permissions.