Need help understanding "zero" on a Fanuc 3T.

I've undertaken a personal project restoring an old Tsugami PL3B lathe with Fanuc 3T
controls. It's taken about 6 months to get it fully operational, and now I'm ready to make
its first cuts since it was torn apart and rebuilt.

Started out like this:


Now looks like:


I'm very familiar with machining centers, but I'm in need of some assistance translating
that into "ancient" CNC lathe operation. Specifically, how the displayed 'zero' is related to
the machine reference coordinates.

When I power the machine on, it sets zero as where-ever the table currently sits.
The first thing I do is zero the axis using the ZRN switch and the JOG buttons.
The ZRN X and Z lights up, but the displayed zero for POS remains the same.

I have not found a way to set the zero outside of the work/tool offsets. And that zero is
relative to the location of the table at poweron, not relative to the absolute machine zero.

I have the original maintenance manual, but I could not find any parameters that seemed relevant.

Any knowledge or assistance provided in understanding this control would be greatly appreciated!

Also, there are a few 900+ options enabled on this control, hopefully there's someone
here who can tell me if anything useful is turned on?