New project x-y grid

I’m new to CNC and have a couple of questions. I started a new project in Easel and set my wood size at 23.5"x23.5"x1" and started my sign. later on when I opened my sign to continue the work the grid I set at 23.5"x23.5"x1" was reduced by about 75% while my project was still at the original measurement settings. Why would the grid reduce??? I need a little help here.