There should be a brand name and model # on the pressure switch. Should be able to find the info doing a search.
If not, one screw will be the pressure, the other will be the differential.
With the tank pumped up to 90, start turning one in, count the turns so you can put it back. It should come on within 2 turns. If not, put it back and try the other. Once you determine which is the pressure screw and which is the differential, you can fine tune it through a few cycles.