When you start a new route, choose the region named Grid Region. Or download one of the dozen or so regions on the DLS with Grid in the title. Once you use a region it remains the default region for new routes and any added baseboards.
If you have already started a route using the textured baseboard, TRS22 has a command under the Display Menu in Surveyor that is Ground, it offers three choices -Textured, Transparent and Grid which will change all existing baseboards to your choice.
I checked and the above command is not in TRS19. The only choice after the fact is to use Edit Route dialog to change the region to one with Grid in the title and any added baseboards will use the grid texture but you can't change existing baseboards except by replacing the texture. There used to be a built-in grid texture but I haven't looked for it in a long time. There are several on the DLS.
I have four grid textures installed in my TRS19. The one named Grid (PBR) when set to zero scale is a perfect match for the grid. I was able to paint over the green texture. Not sure about bulk replace as the scale has to be set to zero to match the real grid texture.