Most of my shooting with an X-T20 is done in program mode, Focus Area set dead in the middle of the viewfinder and as small as it will go, and Single Point Autofocus mode. Sometimes without knowingly doing anything the Focus Area has gotten larger and has shifted far away from the center, usually to as high as it can go and off to either side. Am I doing something to cause this? If so, is there a cure? Thanks.