Problem with setup

I have a problem, I went out to the workshop during the big freeze and had a problem getting the computer to fire up, when I got it going it would not talk to the laser, when I sorted that I found that the Lightburn settings had changed themselves the first thing i noticed was the Lightburn symbol was missing (I don’t know how to get it back) but thats the least of my problems, In the grid each square represents only 1mm instead of 10mm, for the last week I have been trying to find the setting to reset it. If anyone can help I would be very grateful, but please be gentle with explanations co’s I’m not that bright