Oxygen sensor locations

What is the actual code? 99% of the time the code does not actually point to a bad sensor. It points to the data the ECM sees as bad. However a lean code could be a vacuum leak, a rich code could be a bad injector. Neither of those would be repaired by changing the sensor. Instead you need to actually look at the data from the sensor to see if it is actually bad, or is it actually something else.
As for the location. Being this is a four cylinder you only have Bank 1. Bank 1 is always on the side of the engine where cylinder one is, that can change depending on the make of the vehicle, Bank 2 would exist on a V, Flat or other multi-bank engine. Then for the sensor numbers, Sensor 1 will be the first one in the exhaust system, and they count up as you go away from the engine. So the one in the manifold on your Escape is B1 S1, The one after the converter is B1 S2 and so on.