Motion sensor in household with large dog

Sorry, this may have been answered, I am new here and can't figure out how to search this forum.

Any way, just installed simplisafe system last week. motion alarm was triggered twice. I figured it was in the room where our roommate, 180lb St.Bernard likes to nap.
It was not triggered by motion sensor or camera in kitchen he does walk there when he wakes up. Is there an adjustment to decentisize sensor?

Thanks in advance.