How change bathymetry data

I started making grid and I was going to use another bathymetry data Gebco compared to defined data in this model etopo2. To deal with this, I have replaced this data with etopo2 in Topo folder and tested many methods. I believe that we should change some variables; however, unfortunately, I could not. Please help me with your interesting comments.

Please replace the file add_topo.m attached with this reply in the preprocessing_tools folder of croco_tools will work for gebco data