Changing a parameter on GE fanuc controller

So we have this machine called a "quickwater" that we use to heat our low pressure water system. On the HMI screen there is a place where you can change the pump mode to either Auto or Manual. Every time power is cycled on the machine, it defaults to auto. The issue with this is that we only want to run it in manual. I want to change it so that it defaults to Manual when you cycle power. How do I do it?
A GE Fanuc VersaMax micro controller runs the system.

You will need to modify the PLC program. You'll have to identify the bit or bits in PLC memory that determines auto or manual mode and make it take the state you need on power-up.

I don't have any experience with GE controllers. Any way you could steer me in the right direction as to how to do that?
Do I need any special cabling?
What software does that controller normally run?

The programming software is called Proficy Machine edition. Communication with that model PLC is serial, not Ethernet, so you will need a serial port on the computer that runs Proficy. That could be a USB/serial converter or a real serial port on an older computer. You can use the 15-pin RS485 port that the HMI is connected to or you can use the RJ45 (serial RS232, not Ethernet) port behind the door to the left of the HMI cable.
Your local distributor can provide the software and the proper cable. Most GEXPRO offices are authorized to sell the product line.
Another alternative would be to try to find a nearby integrator with GE experience who can come in and do the job for you. Based on your description of what you want to do, I doubt if it would take more than a few hours for someone with GE experience. Assuming you're in Florence Kentucky your proximity to GE Aircraft Engines in Evendale Ohio and GE Appliance Park in Louisville means there should be more than a few people familiar with GE PLCs nearby. GE's corporate policy was to specify OEMs of equipment for their factories use GE PLCs.