Barometer accuracy

Hello. On the picture I compare ambient and baro pressure on FR935 (left side) and fenix 5 plus (right side). Both watches are calibrates at the same altitud. I checked on nearest weather station and pressure on fenix 5 plus is correct. If i calibrate baro pressure on the FR935 the ambiant pressure won't change. So the gap between ambiant and baro will increase... this is not good. How do you explain wrong data on FR935? How can i calibrate ambient pressure? I also wonder me what is the procedure to calibrate baro pressure? Thanks.