What O2 sensor is BANK 1, SENSOR 1

I have the 2.5 liter V-6. Engine check lite came on. Code reader says P0134 error, O2 sensor signal remains at center, BANK 1, SENSOR 1.
I only have 2 O2 sensors on car, 1 BEFORE catalytic convertor and one AFTER cat.

Which O2 sensor is BANK 1, SENSER 1?

I have replaced one BEFORE cat with OEM one, but still get same error code.
Also a few of my MONITOR test show on code reader as 'NOT COMPLETE' - how do I reset all monitors? Apparently all these monitors are RE-SET when ign. Key is turned off.
Thanks