The view used on category and post type pages is the Layout setting of the GD > Loop block on the GD Archive template page. Search results use the same block on the search page. Change it in both places to make three columns the default.
- Go to GeoDirectory > Settings > General > Pages and note which pages are set as the Archive page and the Search Page.
- Edit the archive page and select the GD > Loop block.
- Set Layout to Grid View (Three Columns) and update the page.
- Do the same on the search page.
If you use shortcodes instead of blocks, the same setting is [gd_loop layout="3"]. Use 0 for a list, or 1 to 5 for that number of columns. The same layout option works on the GD > Listings shortcode for lists on other pages.
Stop visitors changing the view
The view switcher is part of the GD > Loop Actions block, which also holds the sort dropdown. In its settings, Hide Layouts lets you pick which views to remove from the switcher, so you can hide List and the other grids and keep only Grid 3. You do not need CSS for this.
A view a visitor picked earlier is remembered in their browser. If you change the default and still see the old view, choose the new view once from the switcher, or check in a private window.
More options: GD > Loop and GD > Loop Actions.